fix: link between parent and child procedure
diff --git a/erpnext/quality_management/doctype/quality_procedure/quality_procedure.py b/erpnext/quality_management/doctype/quality_procedure/quality_procedure.py
index e860408..6834abc 100644
--- a/erpnext/quality_management/doctype/quality_procedure/quality_procedure.py
+++ b/erpnext/quality_management/doctype/quality_procedure/quality_procedure.py
@@ -16,16 +16,13 @@
 	def on_update(self):
 		NestedSet.on_update(self)
 		self.set_parent()
+		self.remove_parent_from_old_child()
+		self.add_child_to_parent()
+		self.remove_child_from_old_parent()
 
 	def after_insert(self):
 		self.set_parent()
-
-		# add child to parent if missing
-		if self.parent_quality_procedure:
-			parent = frappe.get_doc("Quality Procedure", self.parent_quality_procedure)
-			if not [d for d in parent.processes if d.procedure == self.name]:
-				parent.append("processes", {"procedure": self.name, "process_description": self.name})
-				parent.save()
+		self.add_child_to_parent()
 
 	def on_trash(self):
 		# clear from child table (sub procedures)
@@ -36,15 +33,6 @@
 		)
 		NestedSet.on_trash(self, allow_root_deletion=True)
 
-	def set_parent(self):
-		for process in self.processes:
-			# Set parent for only those children who don't have a parent
-			has_parent = frappe.db.get_value(
-				"Quality Procedure", process.procedure, "parent_quality_procedure"
-			)
-			if not has_parent and process.procedure:
-				frappe.db.set_value(self.doctype, process.procedure, "parent_quality_procedure", self.name)
-
 	def check_for_incorrect_child(self):
 		for process in self.processes:
 			if process.procedure:
@@ -61,6 +49,48 @@
 						title=_("Invalid Child Procedure"),
 					)
 
+	def set_parent(self):
+		"""Set `Parent Procedure` in `Child Procedures`"""
+
+		for process in self.processes:
+			if process.procedure:
+				if not frappe.db.get_value("Quality Procedure", process.procedure, "parent_quality_procedure"):
+					frappe.db.set_value(
+						"Quality Procedure", process.procedure, "parent_quality_procedure", self.name
+					)
+
+	def remove_parent_from_old_child(self):
+		"""Remove `Parent Procedure` from `Old Child Procedures`"""
+
+		if old_doc := self.get_doc_before_save():
+			if old_child_procedures := set([d.procedure for d in old_doc.processes if d.procedure]):
+				current_child_procedures = set([d.procedure for d in self.processes if d.procedure])
+
+				if removed_child_procedures := list(old_child_procedures.difference(current_child_procedures)):
+					for child_procedure in removed_child_procedures:
+						frappe.db.set_value("Quality Procedure", child_procedure, "parent_quality_procedure", None)
+
+	def add_child_to_parent(self):
+		"""Add `Child Procedure` to `Parent Procedure`"""
+
+		if self.parent_quality_procedure:
+			parent = frappe.get_doc("Quality Procedure", self.parent_quality_procedure)
+			if not [d for d in parent.processes if d.procedure == self.name]:
+				parent.append("processes", {"procedure": self.name, "process_description": self.name})
+				parent.save()
+
+	def remove_child_from_old_parent(self):
+		"""Remove `Child Procedure` from `Old Parent Procedure`"""
+
+		if old_doc := self.get_doc_before_save():
+			if old_parent := old_doc.parent_quality_procedure:
+				if self.parent_quality_procedure != old_parent:
+					parent = frappe.get_doc("Quality Procedure", old_parent)
+					for process in parent.processes:
+						if process.procedure == self.name:
+							parent.remove(process)
+					parent.save()
+
 
 @frappe.whitelist()
 def get_children(doctype, parent=None, parent_quality_procedure=None, is_root=False):