diff --git a/src/Entity.php b/src/Entity.php
index c86cfc9..51fa2d2 100644
--- a/src/Entity.php
+++ b/src/Entity.php
@@ -522,18 +522,6 @@ public function addChildren(array $children, ?int $from = null): static
         return $this;
     }
 
-    /**
-     * Appends the given entity to the children relation.
-     *
-     * @internal
-     */
-    public function appendChild(self $entity): static
-    {
-        $this->getChildrenRelation()->add($entity);
-
-        return $this;
-    }
-
     private function getChildrenRelation(): EntityCollection
     {
         if (!$this->relationLoaded(static::CHILDREN_RELATION_NAME)) {
diff --git a/src/EntityCollection.php b/src/EntityCollection.php
index ed0f736..5ee9ef7 100644
--- a/src/EntityCollection.php
+++ b/src/EntityCollection.php
@@ -137,7 +137,13 @@ protected function makeTree(array $items): array
             $parentId = $item->parent_id;
 
             if (array_key_exists($parentId, $result)) {
-                $result[$parentId]->appendChild($item);
+                $parent = $result[$parentId];
+                $children = $parent->relationLoaded(Entity::CHILDREN_RELATION_NAME)
+                    ? $parent->getRelation(Entity::CHILDREN_RELATION_NAME)
+                    : new EntityCollection();
+
+                $children->add($item);
+                $parent->setRelation(Entity::CHILDREN_RELATION_NAME, $children);
             } else {
                 $tops[] = $item;
             }