diff --git a/trytond/model/fields/many2many.py b/trytond/model/fields/many2many.py
index 09195c6784..d8369f36e4 100644
--- a/trytond/model/fields/many2many.py
+++ b/trytond/model/fields/many2many.py
@@ -233,14 +233,15 @@ class Many2Many(Field):
                 action = value[0]
                 args = value[1:]
                 actions[action](ids, *args)
-        if relation_to_create:
-            Relation.create(relation_to_create)
+        # Ordered operations to avoid uniqueness/overlapping constraints
         if relation_to_delete:
             Relation.delete(relation_to_delete)
-        if target_to_write:
-            Target.write(*target_to_write)
         if target_to_delete:
             Target.delete(target_to_delete)
+        if target_to_write:
+            Target.write(*target_to_write)
+        if relation_to_create:
+            Relation.create(relation_to_create)
 
     def get_target(self):
         'Return the target model'
diff --git a/trytond/model/fields/one2many.py b/trytond/model/fields/one2many.py
index 39ac0e8dcc..605ffadbb7 100644
--- a/trytond/model/fields/one2many.py
+++ b/trytond/model/fields/one2many.py
@@ -213,12 +213,13 @@ class One2Many(Field):
                 action = value[0]
                 args = value[1:]
                 actions[action](ids, *args)
-        if to_create:
-            Target.create(to_create)
-        if to_write:
-            Target.write(*to_write)
+        # Ordered operations to avoid uniqueness/overlapping constraints
         if to_delete:
             Target.delete(to_delete)
+        if to_write:
+            Target.write(*to_write)
+        if to_create:
+            Target.create(to_create)
 
     def get_target(self):
         'Return the target Model'
diff --git a/trytond/model/fields/one2one.py b/trytond/model/fields/one2one.py
index 3b9e322f5a..c32ffb0c8a 100644
--- a/trytond/model/fields/one2one.py
+++ b/trytond/model/fields/one2one.py
@@ -47,6 +47,7 @@ class One2One(Many2Many):
                             self.origin: record_id,
                             self.target: value,
                             })
+        # Ordered operations to avoid uniqueness/overlapping constraints
         if to_delete:
             Relation.delete(to_delete)
         if to_create: