diff --git a/go.mod b/go.mod
index 8d87e848ae..d09a3d2a79 100644
--- a/go.mod
+++ b/go.mod
@@ -13,6 +13,7 @@ require (
 	github.com/google/cel-go v0.28.0
 	github.com/google/go-cmp v0.7.0
 	github.com/google/go-github/scrape v0.0.0-20260403152401-96a365122246
+	github.com/google/go-github/v84 v84.0.0
 	github.com/google/go-github/v85 v85.0.0
 	github.com/hako/durafmt v0.0.0-20210608085754-5c1018a4e16b
 	github.com/jenkins-x/go-scm v1.15.17
@@ -78,7 +79,6 @@ require (
 	github.com/go-openapi/swag/typeutils v0.25.5 // indirect
 	github.com/go-openapi/swag/yamlutils v0.25.5 // indirect
 	github.com/go-viper/mapstructure/v2 v2.5.0 // indirect
-	github.com/google/go-github/v84 v84.0.0 // indirect
 	github.com/oklog/ulid/v2 v2.1.1 // indirect
 	github.com/prometheus/otlptranslator v1.0.0 // indirect
 	github.com/rickb777/plural v1.4.10 // indirect
diff --git a/pkg/provider/bitbucketdatacenter/bitbucketdatacenter.go b/pkg/provider/bitbucketdatacenter/bitbucketdatacenter.go
index 97a39460b8..0637d611e5 100644
--- a/pkg/provider/bitbucketdatacenter/bitbucketdatacenter.go
+++ b/pkg/provider/bitbucketdatacenter/bitbucketdatacenter.go
@@ -41,6 +41,7 @@ type Provider struct {
 	apiURL                    string
 	provenance                string
 	projectKey                string
+	previousHeadCommit        string
 	repo                      *v1alpha1.Repository
 	triggerEvent              string
 	cachedChangedFiles        *changedfiles.ChangedFiles
@@ -422,7 +423,13 @@ func (v *Provider) fetchChangedFiles(ctx context.Context, runevent *info.Event)
 	case triggertype.Push:
 		opts := &scm.ListOptions{Page: 1, Size: apiResponseLimit}
 		for {
-			changes, _, err := v.Client().Git.ListChanges(ctx, orgAndRepo, runevent.SHA, opts)
+			var changes []*scm.Change
+			var err error
+			if v.previousHeadCommit != "" {
+				changes, _, err = v.getMergeCommitChanges(ctx, runevent.Organization, runevent.Repository, v.previousHeadCommit, runevent.SHA, opts)
+			} else {
+				changes, _, err = v.Client().Git.ListChanges(ctx, orgAndRepo, runevent.SHA, opts)
+			}
 			if err != nil {
 				return changedfiles.ChangedFiles{}, fmt.Errorf("failed to list changes for commit %s: %w", runevent.SHA, err)
 			}
diff --git a/pkg/provider/bitbucketdatacenter/bitbucketdatacenter_test.go b/pkg/provider/bitbucketdatacenter/bitbucketdatacenter_test.go
index a671bd9e16..20ec221e98 100644
--- a/pkg/provider/bitbucketdatacenter/bitbucketdatacenter_test.go
+++ b/pkg/provider/bitbucketdatacenter/bitbucketdatacenter_test.go
@@ -21,6 +21,7 @@ import (
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/params/settings"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/params/triggertype"
 	bbtest "github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/test"
+	bbtypes "github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/types"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/provider/status"
 	"go.opentelemetry.io/otel"
 
@@ -707,40 +708,62 @@ func TestGetFiles(t *testing.T) {
 		PullRequestNumber: 1,
 	}
 
-	pushFiles := []*bbtest.DiffStat{
+	pushFiles := []*bbtypes.DiffStat{
 		{
-			Path: bbtest.DiffPath{ToString: "added.md"},
+			Path: bbtypes.DiffPath{ToString: "added.md"},
 			Type: "ADD",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "modified.txt"},
+			Path: bbtypes.DiffPath{ToString: "modified.txt"},
 			Type: "MODIFY",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "renamed.yaml"},
+			Path: bbtypes.DiffPath{ToString: "renamed.yaml"},
 			Type: "MOVE",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "deleted.go"},
+			Path: bbtypes.DiffPath{ToString: "deleted.go"},
 			Type: "DELETE",
 		},
 	}
 
-	pullRequestFiles := []*bbtest.DiffStat{
+	pullRequestFiles := []*bbtypes.DiffStat{
 		{
-			Path: bbtest.DiffPath{ToString: "added.go"},
+			Path: bbtypes.DiffPath{ToString: "added.go"},
 			Type: "ADD",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "modified.yaml"},
+			Path: bbtypes.DiffPath{ToString: "modified.yaml"},
 			Type: "MODIFY",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "renamed.txt"},
+			Path: bbtypes.DiffPath{ToString: "renamed.txt"},
 			Type: "MOVE",
 		},
 		{
-			Path: bbtest.DiffPath{ToString: "deleted.md"},
+			Path: bbtypes.DiffPath{ToString: "deleted.md"},
+			Type: "DELETE",
+		},
+	}
+
+	mergeCommitPushEvent := &info.Event{
+		SHA:           "MERGESHA456",
+		Organization:  "pac",
+		Repository:    "test",
+		TriggerTarget: triggertype.Push,
+	}
+
+	mergeCommitFiles := []*bbtypes.DiffStat{
+		{
+			Path: bbtypes.DiffPath{ToString: "merge-added.go"},
+			Type: "ADD",
+		},
+		{
+			Path: bbtypes.DiffPath{ToString: "merge-modified.txt"},
+			Type: "MODIFY",
+		},
+		{
+			Path: bbtypes.DiffPath{ToString: "merge-deleted.md"},
 			Type: "DELETE",
 		},
 	}
@@ -748,7 +771,8 @@ func TestGetFiles(t *testing.T) {
 	tests := []struct {
 		name                   string
 		event                  *info.Event
-		changeFiles            []*bbtest.DiffStat
+		changeFiles            []*bbtypes.DiffStat
+		previousHeadCommit     string
 		wantAddedFilesCount    int
 		wantDeletedFilesCount  int
 		wantModifiedFilesCount int
@@ -794,6 +818,23 @@ func TestGetFiles(t *testing.T) {
 			wantError:              true,
 			errMsg:                 "failed to list changes for pull request: No message available",
 		},
+		{
+			name:                   "good/merge commit push event",
+			event:                  mergeCommitPushEvent,
+			changeFiles:            mergeCommitFiles,
+			previousHeadCommit:     "PREVIOUSHEAD789",
+			wantAddedFilesCount:    1,
+			wantDeletedFilesCount:  1,
+			wantModifiedFilesCount: 1,
+			wantRenamedFilesCount:  0,
+		},
+		{
+			name:               "bad/merge commit push event api error",
+			event:              mergeCommitPushEvent,
+			previousHeadCommit: "PREVIOUSHEAD789",
+			wantError:          true,
+			errMsg:             "failed to list changes for commit MERGESHA456: failed to get merge commit changes: status code: 401",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -801,11 +842,25 @@ func TestGetFiles(t *testing.T) {
 			client, mux, tearDown, tURL := bbtest.SetupBBDataCenterClient()
 			defer tearDown()
 
-			stats := &bbtest.DiffStats{
+			stats := &bbtypes.DiffStats{
+				Pagination: bbtypes.Pagination{
+					LastPage: true,
+				},
 				Values: tt.changeFiles,
 			}
 
-			if tt.event.TriggerTarget == triggertype.Push {
+			if tt.event.TriggerTarget == triggertype.Push && tt.previousHeadCommit != "" {
+				mux.HandleFunc("/projects/pac/repos/test/changes", func(w http.ResponseWriter, r *http.Request) {
+					if tt.wantError {
+						w.WriteHeader(http.StatusUnauthorized)
+						return
+					}
+					assert.Equal(t, r.URL.Query().Get("since"), tt.previousHeadCommit)
+					assert.Equal(t, r.URL.Query().Get("until"), tt.event.SHA)
+					b, _ := json.Marshal(stats)
+					fmt.Fprint(w, string(b))
+				})
+			} else if tt.event.TriggerTarget == triggertype.Push {
 				mux.HandleFunc("/projects/pac/repos/test/commits/IAMSHA123/changes", func(w http.ResponseWriter, _ *http.Request) {
 					if tt.wantError {
 						w.WriteHeader(http.StatusUnauthorized)
@@ -831,7 +886,7 @@ func TestGetFiles(t *testing.T) {
 			provider := sdkmetric.NewMeterProvider(sdkmetric.WithReader(reader))
 			otel.SetMeterProvider(provider)
 
-			v := &Provider{client: client, baseURL: tURL, triggerEvent: string(tt.event.TriggerTarget)}
+			v := &Provider{client: client, baseURL: tURL, triggerEvent: string(tt.event.TriggerTarget), previousHeadCommit: tt.previousHeadCommit}
 			changedFiles, err := v.GetFiles(ctx, tt.event)
 			if tt.wantError {
 				assert.Equal(t, err.Error(), tt.errMsg)
@@ -855,33 +910,37 @@ func TestGetFiles(t *testing.T) {
 				}
 			}
 
-			var rm metricdata.ResourceMetrics
-			err = reader.Collect(ctx, &rm)
-			assert.NilError(t, err, "error collecting metrics")
-
-			assert.Equal(t, len(rm.ScopeMetrics), 1)
-			assert.Equal(t, len(rm.ScopeMetrics[0].Metrics), 1)
-			assert.Equal(t, rm.ScopeMetrics[0].Metrics[0].Name, "pipelines_as_code_git_provider_api_request_count")
-			count, ok := rm.ScopeMetrics[0].Metrics[0].Data.(metricdata.Sum[int64])
-			assert.Assert(t, ok)
-			assert.Equal(t, count.DataPoints[0].Value, int64(1))
-
-			_, _ = v.GetFiles(ctx, tt.event)
-			// recollect the metrics af
-			err = reader.Collect(ctx, &rm)
-			assert.NilError(t, err, "error collecting metrics")
-
-			assert.Equal(t, len(rm.ScopeMetrics), 1)
-			assert.Equal(t, len(rm.ScopeMetrics[0].Metrics), 1)
-			assert.Equal(t, rm.ScopeMetrics[0].Metrics[0].Name, "pipelines_as_code_git_provider_api_request_count")
-			count, ok = rm.ScopeMetrics[0].Metrics[0].Data.(metricdata.Sum[int64])
-			assert.Assert(t, ok)
-			if tt.wantError {
-				// no caching on error so we expect 2 metrics
-				assert.Equal(t, count.DataPoints[0].Value, int64(2))
-			} else {
-				// caching on success so we expect 1 metric
+			// getMergeCommitChanges uses v.client.Do directly (not v.Client()),
+			// so no API usage metrics are recorded for that path.
+			if tt.previousHeadCommit == "" {
+				var rm metricdata.ResourceMetrics
+				err = reader.Collect(ctx, &rm)
+				assert.NilError(t, err, "error collecting metrics")
+
+				assert.Equal(t, len(rm.ScopeMetrics), 1)
+				assert.Equal(t, len(rm.ScopeMetrics[0].Metrics), 1)
+				assert.Equal(t, rm.ScopeMetrics[0].Metrics[0].Name, "pipelines_as_code_git_provider_api_request_count")
+				count, ok := rm.ScopeMetrics[0].Metrics[0].Data.(metricdata.Sum[int64])
+				assert.Assert(t, ok)
 				assert.Equal(t, count.DataPoints[0].Value, int64(1))
+
+				_, _ = v.GetFiles(ctx, tt.event)
+				// recollect the metrics af
+				err = reader.Collect(ctx, &rm)
+				assert.NilError(t, err, "error collecting metrics")
+
+				assert.Equal(t, len(rm.ScopeMetrics), 1)
+				assert.Equal(t, len(rm.ScopeMetrics[0].Metrics), 1)
+				assert.Equal(t, rm.ScopeMetrics[0].Metrics[0].Name, "pipelines_as_code_git_provider_api_request_count")
+				count, ok = rm.ScopeMetrics[0].Metrics[0].Data.(metricdata.Sum[int64])
+				assert.Assert(t, ok)
+				if tt.wantError {
+					// no caching on error so we expect 2 metrics
+					assert.Equal(t, count.DataPoints[0].Value, int64(2))
+				} else {
+					// caching on success so we expect 1 metric
+					assert.Equal(t, count.DataPoints[0].Value, int64(1))
+				}
 			}
 		})
 	}
diff --git a/pkg/provider/bitbucketdatacenter/diff_api.go b/pkg/provider/bitbucketdatacenter/diff_api.go
new file mode 100644
index 0000000000..2da9d05314
--- /dev/null
+++ b/pkg/provider/bitbucketdatacenter/diff_api.go
@@ -0,0 +1,89 @@
+package bitbucketdatacenter
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"github.com/jenkins-x/go-scm/scm"
+	"github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/types"
+)
+
+// getMergeCommitChanges gets the changes between two commits for a merge commit.
+// this endpoint is not implemented in the go-scm package, so we need to use the raw HTTP request.
+// but we're using the client from the go-scm package to make the request.
+func (v *Provider) getMergeCommitChanges(ctx context.Context, org, repo, fromCommit, toCommit string, opts *scm.ListOptions) ([]*scm.Change, *scm.Response, error) {
+	params := url.Values{}
+	params.Set("since", fromCommit)
+	params.Set("until", toCommit)
+	params.Set("start", fmt.Sprintf("%d", (opts.Page-1)*opts.Size))
+	params.Set("limit", fmt.Sprintf("%d", opts.Size))
+	path := fmt.Sprintf("rest/api/1.0/projects/%s/repos/%s/changes?%s",
+		url.PathEscape(org),
+		url.PathEscape(repo),
+		params.Encode())
+
+	resp, err := v.Client().Do(ctx, &scm.Request{
+		Method: "GET",
+		Path:   path,
+		Header: http.Header{
+			"Content-Type":      {"application/json"},
+			"x-atlassian-token": {"no-check"},
+		},
+	})
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to get merge commit changes: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.Status > 300 {
+		var errResp struct {
+			Errors []struct {
+				Message string `json:"message"`
+			} `json:"errors"`
+		}
+		errMsg := fmt.Sprintf("status code: %d", resp.Status)
+		if decErr := json.NewDecoder(resp.Body).Decode(&errResp); decErr == nil && len(errResp.Errors) > 0 {
+			errMsg = fmt.Sprintf("%s, message: %s", errMsg, errResp.Errors[0].Message)
+		}
+		return nil, nil, fmt.Errorf("failed to get merge commit changes: %s", errMsg)
+	}
+
+	out := new(types.DiffStats)
+
+	err = json.NewDecoder(resp.Body).Decode(out)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to decode merge commit changes: %w", err)
+	}
+
+	if !out.LastPage {
+		resp.Page.First = 1
+		resp.Page.Next = opts.Page + 1
+	}
+
+	return convertDiffstats(out), resp, nil
+}
+
+func convertDiffstats(from *types.DiffStats) []*scm.Change {
+	to := make([]*scm.Change, 0, len(from.Values))
+	for _, v := range from.Values {
+		to = append(to, convertDiffstat(v))
+	}
+	return to
+}
+
+func convertDiffstat(from *types.DiffStat) *scm.Change {
+	to := &scm.Change{
+		Path:     from.Path.ToString,
+		Added:    from.Type == "ADD",
+		Modified: from.Type == "MODIFY",
+		Renamed:  from.Type == "MOVE",
+		Deleted:  from.Type == "DELETE",
+	}
+	if from.SrcPath != nil {
+		to.PreviousPath = from.SrcPath.ToString
+	}
+	return to
+}
diff --git a/pkg/provider/bitbucketdatacenter/diff_api_test.go b/pkg/provider/bitbucketdatacenter/diff_api_test.go
new file mode 100644
index 0000000000..802006bbc9
--- /dev/null
+++ b/pkg/provider/bitbucketdatacenter/diff_api_test.go
@@ -0,0 +1,195 @@
+package bitbucketdatacenter
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/jenkins-x/go-scm/scm"
+	bbtest "github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/test"
+	bbtypes "github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/types"
+	"gotest.tools/v3/assert"
+	rtesting "knative.dev/pkg/reconciler/testing"
+)
+
+func TestGetMergeCommitChanges(t *testing.T) {
+	tests := []struct {
+		name             string
+		fromCommit       string
+		toCommit         string
+		diffStats        *bbtypes.DiffStats
+		wantChangesCount int
+		wantAdded        int
+		wantModified     int
+		wantRenamed      int
+		wantDeleted      int
+		wantPreviousPath string
+		wantErr          string
+		apiStatusCode    int
+		setup            func(t *testing.T, mux *http.ServeMux)
+	}{
+		{
+			name:       "good/single page of changes",
+			fromCommit: "abc123",
+			toCommit:   "def456",
+			diffStats: &bbtypes.DiffStats{
+				Pagination: bbtypes.Pagination{
+					Start:    0,
+					Size:     4,
+					Limit:    100,
+					LastPage: true,
+				},
+				Values: []*bbtypes.DiffStat{
+					{Path: bbtypes.DiffPath{ToString: "added.go"}, Type: "ADD"},
+					{Path: bbtypes.DiffPath{ToString: "modified.txt"}, Type: "MODIFY"},
+					{Path: bbtypes.DiffPath{ToString: "renamed.yaml"}, Type: "MOVE"},
+					{Path: bbtypes.DiffPath{ToString: "deleted.md"}, Type: "DELETE"},
+				},
+			},
+			wantChangesCount: 4,
+			wantAdded:        1,
+			wantModified:     1,
+			wantRenamed:      1,
+			wantDeleted:      1,
+		},
+		{
+			name:       "good/empty changes",
+			fromCommit: "abc123",
+			toCommit:   "def456",
+			diffStats: &bbtypes.DiffStats{
+				Pagination: bbtypes.Pagination{
+					Start:    0,
+					Size:     0,
+					Limit:    100,
+					LastPage: true,
+				},
+				Values: []*bbtypes.DiffStat{},
+			},
+			wantChangesCount: 0,
+		},
+		{
+			name:       "good/change with srcPath for rename",
+			fromCommit: "abc123",
+			toCommit:   "def456",
+			diffStats: &bbtypes.DiffStats{
+				Pagination: bbtypes.Pagination{
+					Start:    0,
+					Size:     1,
+					Limit:    100,
+					LastPage: true,
+				},
+				Values: []*bbtypes.DiffStat{
+					{
+						Path:    bbtypes.DiffPath{ToString: "new/path.go"},
+						SrcPath: &bbtypes.DiffPath{ToString: "old/path.go"},
+						Type:    "MOVE",
+					},
+				},
+			},
+			wantChangesCount: 1,
+			wantRenamed:      1,
+			wantPreviousPath: "old/path.go",
+		},
+		{
+			name:          "bad/api returns error status",
+			fromCommit:    "abc123",
+			toCommit:      "def456",
+			apiStatusCode: http.StatusBadRequest,
+			wantErr:       "failed to get merge commit changes: status code: 400",
+		},
+		{
+			name:       "bad/api returns invalid json",
+			fromCommit: "abc123",
+			toCommit:   "def456",
+			setup: func(t *testing.T, mux *http.ServeMux) {
+				t.Helper()
+				mux.HandleFunc("/projects/owner/repos/repo/changes", func(w http.ResponseWriter, _ *http.Request) {
+					fmt.Fprint(w, "invalid json{{{")
+				})
+			},
+			wantErr: "failed to decode merge commit changes",
+		},
+		{
+			name:       "good/pagination sets next page",
+			fromCommit: "abc123",
+			toCommit:   "def456",
+			diffStats: &bbtypes.DiffStats{
+				Pagination: bbtypes.Pagination{
+					Start:    0,
+					Size:     100,
+					Limit:    100,
+					LastPage: false,
+					NextPage: 100,
+				},
+				Values: []*bbtypes.DiffStat{
+					{Path: bbtypes.DiffPath{ToString: "file.go"}, Type: "ADD"},
+				},
+			},
+			wantChangesCount: 1,
+			wantAdded:        1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx, _ := rtesting.SetupFakeContext(t)
+			client, mux, tearDown, _ := bbtest.SetupBBDataCenterClient()
+			defer tearDown()
+
+			if tt.setup != nil {
+				tt.setup(t, mux)
+			} else {
+				mux.HandleFunc("/projects/owner/repos/repo/changes", func(w http.ResponseWriter, r *http.Request) {
+					if tt.apiStatusCode != 0 {
+						w.WriteHeader(tt.apiStatusCode)
+						return
+					}
+					assert.Equal(t, r.URL.Query().Get("since"), tt.fromCommit)
+					assert.Equal(t, r.URL.Query().Get("until"), tt.toCommit)
+					b, err := json.Marshal(tt.diffStats)
+					assert.NilError(t, err)
+					fmt.Fprint(w, string(b))
+				})
+			}
+
+			v := &Provider{client: client}
+			opts := &scm.ListOptions{Page: 1, Size: apiResponseLimit}
+			changes, resp, err := v.getMergeCommitChanges(ctx, "owner", "repo", tt.fromCommit, tt.toCommit, opts)
+			if tt.wantErr != "" {
+				assert.ErrorContains(t, err, tt.wantErr)
+				return
+			}
+			assert.NilError(t, err)
+			assert.Equal(t, tt.wantChangesCount, len(changes))
+
+			added, modified, renamed, deleted := 0, 0, 0, 0
+			for _, c := range changes {
+				if c.Added {
+					added++
+				}
+				if c.Modified {
+					modified++
+				}
+				if c.Renamed {
+					renamed++
+				}
+				if c.Deleted {
+					deleted++
+				}
+			}
+			assert.Equal(t, tt.wantAdded, added)
+			assert.Equal(t, tt.wantModified, modified)
+			assert.Equal(t, tt.wantRenamed, renamed)
+			assert.Equal(t, tt.wantDeleted, deleted)
+
+			if tt.wantPreviousPath != "" {
+				assert.Equal(t, tt.wantPreviousPath, changes[0].PreviousPath)
+			}
+
+			if tt.diffStats != nil && !tt.diffStats.LastPage {
+				assert.Equal(t, 1, resp.Page.First)
+				assert.Equal(t, 2, resp.Page.Next)
+			}
+		})
+	}
+}
diff --git a/pkg/provider/bitbucketdatacenter/parse_payload.go b/pkg/provider/bitbucketdatacenter/parse_payload.go
index 975cbd74be..46e67fa923 100644
--- a/pkg/provider/bitbucketdatacenter/parse_payload.go
+++ b/pkg/provider/bitbucketdatacenter/parse_payload.go
@@ -175,6 +175,22 @@ func (v *Provider) ParsePayload(_ context.Context, _ *params.Run, request *http.
 			return nil, fmt.Errorf("push event contains no commits; cannot proceed")
 		}
 
+		// In Bitbucket Data Center, when a pull request is merged, it creates two commits in the repository:
+		// 1. A merge commit, which is represented by `changes[0].ToHash`.
+		// 2. The actual commit containing the changes from the source branch.
+		//
+		// However, the merge commit often does not contain any file changes itself,
+		// which can cause issues when determining whether file modifications should trigger PipelineRuns.
+		//
+		// Typically, a regular (non-merge) commit has a single parent, but a merge commit has two parents:
+		// - The first parent is the previous HEAD of the destination branch (the branch into which the PR was merged).
+		// - The second parent is the HEAD of the source branch (the branch being merged).
+		//
+		// if we detect a merge commit, we will use the previous HEAD commit to get changes from the previous HEAD to the current HEAD.
+		if len(e.Commits) > 1 && len(e.Commits[0].Parents) > 1 {
+			v.previousHeadCommit = e.Commits[0].Parents[0].ID
+		}
+
 		processedEvent.SHA = e.Changes[0].ToHash
 		processedEvent.URL = e.Repository.Links.Self[0].Href
 		processedEvent.BaseBranch = e.Changes[0].RefID
diff --git a/pkg/provider/bitbucketdatacenter/test/test_types.go b/pkg/provider/bitbucketdatacenter/test/test_types.go
index 9f63400501..ef0eab782c 100644
--- a/pkg/provider/bitbucketdatacenter/test/test_types.go
+++ b/pkg/provider/bitbucketdatacenter/test/test_types.go
@@ -2,29 +2,6 @@ package test
 
 import "github.com/openshift-pipelines/pipelines-as-code/pkg/provider/bitbucketdatacenter/types"
 
-type Pagination struct {
-	Start    int  `json:"start"`
-	Size     int  `json:"size"`
-	Limit    int  `json:"limit"`
-	LastPage bool `json:"isLastPage"`
-	NextPage int  `json:"nextPageStart"`
-}
-
-type DiffPath struct {
-	ToString string `json:"toString"`
-}
-
-type DiffStat struct {
-	Path    DiffPath  `json:"path"`
-	SrcPath *DiffPath `json:"srcPath,omitempty"` // used in lib that's why leaving it here nil
-	Type    string    `json:"type"`
-}
-
-type DiffStats struct {
-	Pagination
-	Values []*DiffStat
-}
-
 type ProjGroup struct {
 	Group      Group  `json:"group"`
 	Permission string `json:"permission"`
diff --git a/pkg/provider/bitbucketdatacenter/types/types.go b/pkg/provider/bitbucketdatacenter/types/types.go
index 94c524e002..d9031a09db 100644
--- a/pkg/provider/bitbucketdatacenter/types/types.go
+++ b/pkg/provider/bitbucketdatacenter/types/types.go
@@ -197,3 +197,43 @@ type ToCommit struct {
 	Commit
 	Parents []Commit `json:"parents"` // Commit also has Parents field, but its Parents has only two fields while actual payload has more.
 }
+
+type Pagination struct {
+	Start    int  `json:"start"`
+	Size     int  `json:"size"`
+	Limit    int  `json:"limit"`
+	LastPage bool `json:"isLastPage"`
+	NextPage int  `json:"nextPageStart"`
+}
+
+type DiffStats struct {
+	Pagination
+	Values []*DiffStat `json:"values"`
+}
+
+type DiffPath struct {
+	Components []string `json:"components"`
+	Parent     string   `json:"parent"`
+	Name       string   `json:"name"`
+	Extension  string   `json:"extension"`
+	ToString   string   `json:"toString"`
+}
+
+type DiffStat struct {
+	ContentID        string    `json:"contentId"`
+	FromContentID    string    `json:"fromContentId"`
+	Path             DiffPath  `json:"path"`
+	SrcPath          *DiffPath `json:"srcPath,omitempty"`
+	PercentUnchanged int       `json:"percentUnchanged"`
+	Type             string    `json:"type"`
+	NodeType         string    `json:"nodeType"`
+	SrcExecutable    bool      `json:"srcExecutable"`
+	Links            struct {
+		Self []struct {
+			Href string `json:"href"`
+		} `json:"self"`
+	} `json:"links"`
+	Properties struct {
+		GitChangeType string `json:"gitChangeType"`
+	} `json:"properties"`
+}
diff --git a/test/bitbucket_datacenter_pull_request_test.go b/test/bitbucket_datacenter_pull_request_test.go
index 7c7ed9f015..56a9670267 100644
--- a/test/bitbucket_datacenter_pull_request_test.go
+++ b/test/bitbucket_datacenter_pull_request_test.go
@@ -8,12 +8,17 @@ import (
 	"os"
 	"testing"
 
+	"github.com/openshift-pipelines/pipelines-as-code/pkg/apis/pipelinesascode/keys"
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/params/triggertype"
 	tbbdc "github.com/openshift-pipelines/pipelines-as-code/test/pkg/bitbucketdatacenter"
+	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/options"
+	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/payload"
 	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/wait"
 
+	"github.com/jenkins-x/go-scm/scm"
 	"github.com/tektoncd/pipeline/pkg/names"
 	"gotest.tools/v3/assert"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 func TestBitbucketDataCenterPullRequest(t *testing.T) {
@@ -34,9 +39,12 @@ func TestBitbucketDataCenterPullRequest(t *testing.T) {
 		files[fmt.Sprintf(".tekton/pipelinerun-%d.yaml", i)] = "testdata/pipelinerun.yaml"
 	}
 
+	files, err = payload.GetEntries(files, targetNS, options.MainBranch, triggertype.PullRequest.String(), map[string]string{})
+	assert.NilError(t, err)
+
 	pr := tbbdc.CreatePR(ctx, t, client, runcnx, opts, repo, files, bitbucketWSOwner, targetNS)
 	runcnx.Clients.Log.Infof("Pull Request with title '%s' is created", pr.Title)
-	defer tbbdc.TearDown(ctx, t, runcnx, client, pr.Number, bitbucketWSOwner, targetNS)
+	defer tbbdc.TearDown(ctx, t, runcnx, client, pr, bitbucketWSOwner, targetNS)
 
 	successOpts := wait.SuccessOpt{
 		TargetNS:        targetNS,
@@ -63,9 +71,12 @@ func TestBitbucketDataCenterCELPathChangeInPullRequest(t *testing.T) {
 		".tekton/pipelinerun.yaml": "testdata/pipelinerun-cel-path-changed.yaml",
 	}
 
+	files, err = payload.GetEntries(files, targetNS, options.MainBranch, triggertype.PullRequest.String(), map[string]string{})
+	assert.NilError(t, err)
+
 	pr := tbbdc.CreatePR(ctx, t, client, runcnx, opts, repo, files, bitbucketWSOwner, targetNS)
 	runcnx.Clients.Log.Infof("Pull Request with title '%s' is created", pr.Title)
-	defer tbbdc.TearDown(ctx, t, runcnx, client, pr.Number, bitbucketWSOwner, targetNS)
+	defer tbbdc.TearDown(ctx, t, runcnx, client, pr, bitbucketWSOwner, targetNS)
 
 	successOpts := wait.SuccessOpt{
 		TargetNS:        targetNS,
@@ -75,3 +86,64 @@ func TestBitbucketDataCenterCELPathChangeInPullRequest(t *testing.T) {
 	}
 	wait.Succeeded(ctx, t, runcnx, opts, successOpts)
 }
+
+func TestBitbucketDataCenterOnPathChangeAnnotationOnPRMerge(t *testing.T) {
+	targetNS := names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("pac-e2e-ns")
+	// this would be a temporary base branch for the pull request we're going to raise
+	// we need this because we're going to merge the pull request so that after test
+	// we can delete the temporary base branch and our main branch should not be affected
+	// by this merge because we run the E2E frequently.
+	tempBaseBranch := names.SimpleNameGenerator.RestrictLengthWithRandomSuffix("pac-e2e-ns")
+
+	ctx := context.Background()
+	bitbucketWSOwner := os.Getenv("TEST_BITBUCKET_DATA_CENTER_E2E_REPOSITORY")
+
+	ctx, runcnx, opts, client, err := tbbdc.Setup(ctx)
+	assert.NilError(t, err)
+
+	repo := tbbdc.CreateCRD(ctx, t, client, runcnx, bitbucketWSOwner, targetNS)
+	runcnx.Clients.Log.Infof("Repository %s has been created", repo.Name)
+	defer tbbdc.TearDownNs(ctx, t, runcnx, targetNS)
+
+	branch, resp, err := client.Git.CreateRef(ctx, bitbucketWSOwner, tempBaseBranch, repo.Branch)
+	assert.NilError(t, err, "error creating branch: http status code: %d : %v", resp.Status, err)
+	runcnx.Clients.Log.Infof("Base branch %s has been created", branch.Name)
+
+	opts.BaseBranch = branch.Name
+
+	if os.Getenv("TEST_NOCLEANUP") != "true" {
+		defer func() {
+			_, err := client.Git.DeleteRef(ctx, bitbucketWSOwner, tempBaseBranch)
+			assert.NilError(t, err, "error deleting branch: http status code: %d : %v", resp.Status, err)
+		}()
+	}
+
+	files := map[string]string{
+		".tekton/pr.yaml":       "testdata/pipelinerun-on-path-change.yaml",
+		"doc/foo/bar/README.md": "README.md",
+	}
+
+	files, err = payload.GetEntries(files, targetNS, tempBaseBranch, triggertype.Push.String(), map[string]string{})
+	assert.NilError(t, err)
+
+	pr := tbbdc.CreatePR(ctx, t, client, runcnx, opts, repo, files, bitbucketWSOwner, targetNS)
+	defer tbbdc.TearDown(ctx, t, runcnx, client, nil, bitbucketWSOwner, targetNS)
+
+	// merge the pull request so that we can get push event.
+	_, err = client.PullRequests.Merge(ctx, bitbucketWSOwner, pr.Number, &scm.PullRequestMergeOptions{})
+	assert.NilError(t, err)
+
+	successOpts := wait.SuccessOpt{
+		TargetNS:        targetNS,
+		OnEvent:         triggertype.Push.String(),
+		NumberofPRMatch: 1,
+		MinNumberStatus: 1,
+	}
+	wait.Succeeded(ctx, t, runcnx, opts, successOpts)
+
+	pipelineRuns, err := runcnx.Clients.Tekton.TektonV1().PipelineRuns(targetNS).List(ctx, metav1.ListOptions{})
+	assert.NilError(t, err)
+	assert.Equal(t, len(pipelineRuns.Items), 1)
+	// check that pipeline run contains on-path-change annotation.
+	assert.Equal(t, pipelineRuns.Items[0].GetAnnotations()[keys.OnPathChange], "[doc/***.md]")
+}
diff --git a/test/bitbucket_datacenter_push_test.go b/test/bitbucket_datacenter_push_test.go
index 5e77e2219f..999528fc04 100644
--- a/test/bitbucket_datacenter_push_test.go
+++ b/test/bitbucket_datacenter_push_test.go
@@ -38,7 +38,7 @@ func TestBitbucketDataCenterCELPathChangeOnPush(t *testing.T) {
 	branch, resp, err := client.Git.CreateRef(ctx, bitbucketWSOwner, targetNS, mainBranchRef)
 	assert.NilError(t, err, "error creating branch: http status code: %d : %v", resp.Status, err)
 	runcnx.Clients.Log.Infof("Branch %s has been created", branch.Name)
-	defer tbbs.TearDown(ctx, t, runcnx, client, -1, bitbucketWSOwner, branch.Name)
+	defer tbbs.TearDown(ctx, t, runcnx, client, nil, bitbucketWSOwner, branch.Name)
 
 	files, err = payload.GetEntries(files, targetNS, branch.Name, triggertype.Push.String(), map[string]string{})
 	assert.NilError(t, err)
diff --git a/test/pkg/bitbucketdatacenter/pr.go b/test/pkg/bitbucketdatacenter/pr.go
index 1a5b1af15f..0f1b2c0221 100644
--- a/test/pkg/bitbucketdatacenter/pr.go
+++ b/test/pkg/bitbucketdatacenter/pr.go
@@ -6,9 +6,7 @@ import (
 	"testing"
 
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/params"
-	"github.com/openshift-pipelines/pipelines-as-code/pkg/params/triggertype"
 	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/options"
-	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/payload"
 	"github.com/openshift-pipelines/pipelines-as-code/test/pkg/scm"
 
 	goscm "github.com/jenkins-x/go-scm/scm"
@@ -16,21 +14,24 @@ import (
 )
 
 func CreatePR(ctx context.Context, t *testing.T, client *goscm.Client, runcnx *params.Run, opts options.E2E, repo *goscm.Repository, files map[string]string, orgAndRepo, targetNS string) *goscm.PullRequest {
-	mainBranchRef := "refs/heads/main"
-	branch, resp, err := client.Git.CreateRef(ctx, orgAndRepo, targetNS, mainBranchRef)
+	baseBranchRef := repo.Branch
+	if opts.BaseBranch != "" {
+		baseBranchRef = opts.BaseBranch
+	}
+
+	branch, resp, err := client.Git.CreateRef(ctx, orgAndRepo, targetNS, baseBranchRef)
 	assert.NilError(t, err, "error creating branch: http status code: %d : %v", resp.Status, err)
 	runcnx.Clients.Log.Infof("Branch %s has been created", branch.Name)
 
-	files, err = payload.GetEntries(files, targetNS, options.MainBranch, triggertype.PullRequest.String(), map[string]string{})
-	assert.NilError(t, err)
 	gitCloneURL, err := scm.MakeGitCloneURL(repo.Clone, opts.UserName, opts.Password)
 	assert.NilError(t, err)
+
 	scmOpts := &scm.Opts{
 		GitURL:        gitCloneURL,
 		Log:           runcnx.Clients.Log,
 		WebURL:        repo.Clone,
 		TargetRefName: targetNS,
-		BaseRefName:   repo.Branch,
+		BaseRefName:   baseBranchRef,
 		CommitTitle:   fmt.Sprintf("commit %s", targetNS),
 	}
 	scm.PushFilesToRefGit(t, scmOpts, files)
@@ -41,7 +42,7 @@ func CreatePR(ctx context.Context, t *testing.T, client *goscm.Client, runcnx *p
 		Title: title,
 		Body:  "Test PAC on bitbucket data center",
 		Head:  targetNS,
-		Base:  "main",
+		Base:  baseBranchRef,
 	}
 	pr, resp, err := client.PullRequests.Create(ctx, orgAndRepo, prOpts)
 	assert.NilError(t, err, "error creating pull request: http status code: %d : %v", resp.Status, err)
diff --git a/test/pkg/bitbucketdatacenter/setup.go b/test/pkg/bitbucketdatacenter/setup.go
index 4acd1b9075..671a7e695f 100644
--- a/test/pkg/bitbucketdatacenter/setup.go
+++ b/test/pkg/bitbucketdatacenter/setup.go
@@ -82,15 +82,16 @@ func TearDownNs(ctx context.Context, t *testing.T, runcnx *params.Run, targetNS
 	repository.NSTearDown(ctx, t, runcnx, targetNS)
 }
 
-func TearDown(ctx context.Context, t *testing.T, runcnx *params.Run, client *scm.Client, prID int, orgAndRepo, ref string) {
+func TearDown(ctx context.Context, t *testing.T, runcnx *params.Run, client *scm.Client, pr *scm.PullRequest, orgAndRepo, ref string) {
 	if os.Getenv("TEST_NOCLEANUP") == "true" {
 		runcnx.Clients.Log.Infof("Not cleaning up and closing PR since TEST_NOCLEANUP is set")
 		return
 	}
 
-	if prID != -1 {
-		runcnx.Clients.Log.Infof("Deleting PR #%d", prID)
-		_, err := client.PullRequests.DeletePullRequest(ctx, orgAndRepo, prID)
+	// in Bitbucket Data Center, merged pull requests cannot be deleted.
+	if pr != nil && !pr.Merged {
+		runcnx.Clients.Log.Infof("Deleting PR #%d", pr.Number)
+		_, err := client.PullRequests.DeletePullRequest(ctx, orgAndRepo, pr.Number)
 		assert.NilError(t, err)
 	}
 
diff --git a/test/pkg/options/options.go b/test/pkg/options/options.go
index 67f565f8f4..64247ff810 100644
--- a/test/pkg/options/options.go
+++ b/test/pkg/options/options.go
@@ -4,6 +4,7 @@ import "github.com/openshift-pipelines/pipelines-as-code/pkg/apis/pipelinesascod
 
 type E2E struct {
 	Repo, Organization string
+	BaseBranch         string
 	DirectWebhook      bool
 	ControllerURL      string
 	Concurrency        int