diff --git a/snpcheck/id_snpcaller_vcfmerge.sh b/snpcheck/id_snpcaller_vcfmerge.sh
index d1787dd02..eb89de8f7 100755
--- a/snpcheck/id_snpcaller_vcfmerge.sh
+++ b/snpcheck/id_snpcaller_vcfmerge.sh
@@ -192,20 +192,25 @@ tumor_col_awk=$((tumor_col + 1))
 na_col_awk=$((na_col + 1))
 ref_col_awk=$((ref_col + 1))
 
-## Step 1: Copy snp genotype (na) col to tumor if tumor col no variant call
-awk -v tum="$tumor_col_awk" -v na="$na_col_awk" 'BEGIN { OFS="\t" }
+## Step 1: Copy snp genotype (na) col to tumor if no variant call in tumor col
+##          + replace remaining ./.'s with default 0/1 (for germline variants)
+awk -v tum="$tumor_col_awk" -v na="$na_col_awk" -v ref="$ref_col_awk" 'BEGIN { OFS="\t" }
   /^##/ { print; next }
   /^#CHROM/ { print; next }
   {
     if ($tum == "./." && $na != "./." && $na != "") {
       $tum = $na
     }
+    else if (index($tum, "./.") > 0) {
+      gsub(/\.\/\./, "0/1", $tum)
+    }
+
     print
   }
 ' "$HOME/${MERGED_OUTPUT_VCF}" > "$HOME/temp_with_na_corrected.vcf"
 
 ## Step 2: Remove ref and NA cols
-awk -v ref="$ref_col_awk" -v na="$na_col_awk" 'BEGIN { OFS="\t" }
+awk -v ref="$ref_col_awk" -v na="$na_col_awk" -v filter="$filter_col_awk" 'BEGIN { OFS="\t" }
   /^##/ { print; next }
   /^#CHROM/ {
     for (i = 1; i <= NF; i++) {
@@ -216,6 +221,7 @@ awk -v ref="$ref_col_awk" -v na="$na_col_awk" 'BEGIN { OFS="\t" }
     next
   }
   {
+    $filter="PASS"
     for (i = 1; i <= NF; i++) {
       if (i != ref && i != na) {
         printf "%s%s", $i, (i == NF || (i+1 == ref || i+1 == na) ? ORS : OFS)
diff --git a/snpcheck/id_snpcaller_vcfmerge_GATK.sh b/snpcheck/id_snpcaller_vcfmerge_GATK.sh
new file mode 100644
index 000000000..8d60eb4d5
--- /dev/null
+++ b/snpcheck/id_snpcaller_vcfmerge_GATK.sh
@@ -0,0 +1,145 @@
+#!/bin/bash
+
+set -euo pipefail
+
+LOCAL_INPUT_DIR="$HOME/input_files"
+mkdir -p "$LOCAL_INPUT_DIR"
+exec > "$LOCAL_INPUT_DIR/snpcaller_merge.log" 2>&1
+
+setname="$1"
+INPUT_DIR="gs://wgs-combined-snps-vcfs/${setname}/inputfiles"
+SAMPLE_BARCODE=$(gsutil cat "$INPUT_DIR/sample_barcode.txt")
+CONVERTED_REPORTING_ID=$(gsutil cat "$INPUT_DIR/converted_reporting_id.txt")
+OUTPUT_BUCKET_NAME=$(gsutil cat "$INPUT_DIR/output_bucket.txt")
+
+# define BAM_TUM path
+BAM_TUM="gs://diagnostic-pipeline-output-prod-1/${setname}/${converted_reporting_id}/aligner/${converted_reporting_id}.bam"
+REFERENCE="gs://common-resources/reference_genome/37/Homo_sapiens.GRCh37.GATK.illumina.fasta"
+
+# Copy input files to local
+gsutil cp "$INPUT_DIR/id_snps_intervals.hg37.bed" "$LOCAL_INPUT_DIR/id_snps_intervals.hg37.bed"
+gsutil cp "$INPUT_DIR/hartwig_snpfile_tum.vcf" "$LOCAL_INPUT_DIR/hartwig_snpfile_tum.vcf"
+gsutil cp "$INPUT_DIR/*.purple.germline.vcf.gz" "$LOCAL_INPUT_DIR/"
+gsutil cp "$INPUT_DIR/*.purple.somatic.vcf.gz" "$LOCAL_INPUT_DIR/"
+gsutil cp "$INPUT_DIR/GenomeAnalysisTK.jar" "$LOCAL_INPUT_DIR/GenomeAnalysisTK.jar"
+
+# Create input file vars
+INTERVALS="$LOCAL_INPUT_DIR/id_snps_intervals.hg37.bed"
+SNP_VCF_TUM="$LOCAL_INPUT_DIR/hartwig_snpfile_tum.vcf"
+GERMLINE_VCF=$(ls $LOCAL_INPUT_DIR/*.purple.germline.vcf.gz | head -n 1)
+SOMATIC_VCF=$(ls $LOCAL_INPUT_DIR/*.purple.somatic.vcf.gz | head -n 1)
+GATK="$LOCAL_INPUT_DIR/GenomeAnalysisTK.jar"
+JAVA=#location java
+
+# Create output file name vars
+SNP_OUTPUT_VCF="${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_snp_genotype_output.vcf"
+MERGED_OUTPUT_VCF="${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_merged.vcf"
+FINAL_OUTPUT_VCF="${LOCAL_INPUT_DIR}/${CONVERTED_REPORTING_ID}.reported.variants.and.snps.vcf"
+
+# GATK HaplotypeCaller (UnifiedGenotyper)
+$JAVA -Xmx20G -jar "$GATK" \
+  -T UnifiedGenotyper \
+  -nct $(nproc) \
+  --input_file "$BAM_TUM" \
+  -o "$SNP_OUTPUT_VCF" \
+  -L "$INTERVALS" \
+  --reference_sequence "$REFERENCE" \
+  --output_mode EMIT_ALL_SITES
+
+# Filter somatic/germline VCFs
+zcat "$SOMATIC_VCF" | grep -E '^#|REPORTED' > "${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_somatic_filtered.vcf"
+zcat "$GERMLINE_VCF" | grep -E '^#|REPORTED' > "${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_germline_filtered.vcf"
+
+# CombineVariants
+$JAVA -jar "$GATK" \
+  -T CombineVariants \
+  -R "$REFERENCE" \
+  --variant "${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_somatic_filtered.vcf" \
+  --variant "${LOCAL_INPUT_DIR}/${SAMPLE_BARCODE}_germline_filtered.vcf" \
+  --variant "$SNP_OUTPUT_VCF" \
+  --variant "$SNP_VCF_TUM" \
+  -o "$MERGED_OUTPUT_VCF" \
+  -genotypeMergeOptions UNSORTED
+
+# Copy NA column to tumor if missing, and clean up VCF
+
+header_line=$(grep -m 1 '^#CHROM' "$MERGED_OUTPUT_VCF")
+IFS=$'\t' read -r -a headers <<< "$header_line"
+
+tumor_col=-1
+na_col=-1
+ref_col=-1
+filter_col=-1
+
+# Identify columns
+for i in "${!headers[@]}"; do
+  col="${headers[$i]}"
+  [[ "$col" == "NA" ]] && na_col=$i
+  [[ "$col" == *"-ref" ]] && ref_col=$i
+  [[ "$col" == "FILTER" ]] && filter_col=$i
+  [[ "$col" != "FORMAT" && ! "$col" =~ ^#?(CHROM|POS|ID|REF|ALT|QUAL|FILTER|INFO)$ && "$col" != "NA" && "$col" != *"-ref" ]] && tumor_col=$i
+done
+
+# Validate
+if [[ $tumor_col -eq -1 || $na_col -eq -1 ]]; then
+  echo "Error: Could not find both tumor and NA columns in the merged VCF."
+  exit 1
+fi
+
+# Convert to 1-based for awk
+(( tumor_col_awk = tumor_col + 1 ))
+(( na_col_awk = na_col + 1 ))
+(( ref_col_awk = ref_col + 1 ))
+(( filter_col_awk = filter_col + 1 ))
+
+# Step 1: Copy NA genotype to tumor if missing, replace remaining ./.
+awk -v tum="$tumor_col_awk" -v na="$na_col_awk" 'BEGIN { OFS="\t" }
+  /^##/ { print; next }
+  /^#CHROM/ { print; next }
+  {
+    if ($tum == "./." && $na != "./." && $na != "") {
+      $tum = $na
+    } else if (index($tum, "./.") > 0) {
+      gsub(/\.\/\./, "0/1", $tum)
+    }
+    print
+  }
+' "$MERGED_OUTPUT_VCF" > "${LOCAL_INPUT_DIR}/temp_with_na_corrected.vcf"
+
+# Step 2: Remove ref and NA columns, set FILTER to PASS
+awk -v ref="$ref_col_awk" -v na="$na_col_awk" '
+BEGIN { OFS="\t" }
+
+/^##/ { print; next }
+
+/^#CHROM/ {
+  out=""
+  for (i=1; i<=NF; i++)
+    if (i!=ref && i!=na)
+      out = out (out ? OFS : "") $i
+  print out
+  next
+}
+
+{
+  out=""
+  for (i=1; i<=NF; i++)
+    if (i!=ref && i!=na)
+      out = out (out ? OFS : "") $i
+  print out
+}
+' temp_with_na_corrected.vcf > final.vcf
+
+# Step 3: Upload final VCF
+gsutil cp "${FINAL_OUTPUT_VCF}" "gs://${OUTPUT_BUCKET_NAME}/${setname}/${FINAL_OUTPUT_VCF}" || {
+  echo "Error: Failed to upload VCF to output bucket"
+  exit 1
+}
+
+gsutil cp "$LOCAL_INPUT_DIR/snpcaller_merge.log" "gs://${OUTPUT_BUCKET_NAME}/${setname}/"
+
+gsutil rm -r "${INPUT_DIR}"
+gsutil rm -r "${LOCAL_INPUT_DIR}"
+
+echo "Final VCF copied to output bucket: gs://${OUTPUT_BUCKET_NAME}/${setname}/${FINAL_OUTPUT_VCF} "
+
diff --git a/snpcheck/id_snpcaller_vcfmerge_prep.sh b/snpcheck/id_snpcaller_vcfmerge_prep.sh
new file mode 100644
index 000000000..73f28113f
--- /dev/null
+++ b/snpcheck/id_snpcaller_vcfmerge_prep.sh
@@ -0,0 +1,84 @@
+#!/bin/bash
+
+# Usage check, only permit 1 or 3 arguments
+if [ "$#" -lt 1 ] || [ "$#" -gt 3 ] || [ "$#" -eq 2 ]; then
+  echo "Usage: <setname> <input-bucket-name> <output-bucket-name>"
+  echo "Ex: 123456_HMFregCORE_FS12345678_CORE0100000 research-pipeline-output-prod-1 example-output-bucket"
+  echo "Input and output bucket-names are optional, defaults to diagnostic-pipeline-output-prod-1 and wgs-combined-snps-vcfs (used in production process)"
+  echo "NOTE: When specifying a bucket, both input and output buckets must be provided."
+  exit 1
+else
+  # Redirect output to log only after usage validated
+  INPUT_DIR="$HOME/inputfiles"
+  mkdir INPUT_DIR
+  exec > "$INPUT_DIR/prepare_inputs.log" 2>&1
+  set -euo pipefail
+fi
+
+setname=$1
+DEFAULT_BUCKET="diagnostic-pipeline-output-prod-1"
+BUCKET_NAME=${2:-$DEFAULT_BUCKET}
+
+DEFAULT_OUTPUT_BUCKET="wgs-combined-snps-vcfs"
+OUTPUT_BUCKET_NAME=${3:-$DEFAULT_OUTPUT_BUCKET}
+
+MOUNT_POINT_BAM="$HOME/testdir/"
+mkdir -p "$INPUT_DIR"
+
+# Get barcodes
+ISOLATION_BARCODE=$(echo "$setname" | cut -d'_' -f4)
+SAMPLE_BARCODE=$(lama_get_patient_reporter_data "${ISOLATION_BARCODE}" | jq .tumorSampleBarcode | tr -d '"')
+HOSPITAL_SAMPLE_LABEL=$(lama_get_patient_reporter_data "${ISOLATION_BARCODE}" | jq -r .hospitalSampleLabel)
+REPORTING_ID=$(lama_get_patient_reporter_data "${ISOLATION_BARCODE}" | jq -r .reportingId)
+
+if [[ -n "$HOSPITAL_SAMPLE_LABEL" && "$HOSPITAL_SAMPLE_LABEL" != "null" ]]; then
+    CONVERTED_REPORTING_ID="${REPORTING_ID}-${HOSPITAL_SAMPLE_LABEL}"
+else
+    CONVERTED_REPORTING_ID="${REPORTING_ID}"
+fi
+
+# Mount buckets
+mkdir -p "${MOUNT_POINT_BAM}"
+
+fusermount -u "${MOUNT_POINT_BAM}" 2>/dev/null || true
+
+gcsfuse --implicit-dirs "${BUCKET_NAME}" "${MOUNT_POINT_BAM}"
+
+# SNP intervals
+cp "/data/resources/reporting-resources/snps/id_snps_intervals.hg37.bed" "$INPUT_DIR/id_snps_intervals.hg37.bed"
+
+# Copy hartwig SNP VCF
+ALL_SNP_VCFS=($(find "${MOUNT_POINT_BAM}${setname}" -type f -path "*/snp_genotype/*output.vcf"))
+
+if [ ${#ALL_SNP_VCFS[@]} -eq 0 ]; then
+  echo "Warning: Geen SNP VCF bestanden gevonden in ${MOUNT_POINT_BAM}${setname}" >&2
+fi
+
+for SNP_VCF_PATH in "${ALL_SNP_VCFS[@]}"; do
+    if [[ "$SNP_VCF_PATH" != *-ref* ]]; then
+        cp "$SNP_VCF_PATH" "$INPUT_DIR/hartwig_snpfile_tum.vcf"
+    fi
+done
+
+
+
+# Purple VCFs
+cp "${MOUNT_POINT_BAM}${setname}/purple/"*.purple.germline.vcf.gz "$INPUT_DIR/"
+cp "${MOUNT_POINT_BAM}${setname}/purple/"*.purple.somatic.vcf.gz "$INPUT_DIR/"
+
+# Save metadata
+echo "$SAMPLE_BARCODE" > "$INPUT_DIR/sample_barcode.txt"
+echo "$CONVERTED_REPORTING_ID" > "$INPUT_DIR/converted_reporting_id.txt"
+echo "$OUTPUT_BUCKET_NAME" > "$INPUT_DIR/output_bucket.txt"
+cp "/data/tools/gatk/3.8.0/GenomeAnalysisTK.jar" "$INPUT_DIR/GenomeAnalysisTK.jar"
+
+gsutil cp -r "${INPUT_DIR}" "gs://${OUTPUT_BUCKET_NAME}/${setname}/"
+gsutil cp  "$INPUT_DIR/prepare_inputs.log" "gs://${OUTPUT_BUCKET_NAME}/${setname}/"
+
+# Unmount & cleanup
+fusermount -u "${MOUNT_POINT_BAM}"
+rm -r "${MOUNT_POINT_BAM}"
+rm -r "${INPUT_DIR}"
+
+echo "Done. Files prepared in: gs://${OUTPUT_BUCKET_NAME}/${setname}/"
+