diff --git a/tryton/gui/window/view_form/model/group.py b/tryton/gui/window/view_form/model/group.py
index 875c85f65a..ecc657ae8a 100644
--- a/tryton/gui/window/view_form/model/group.py
+++ b/tryton/gui/window/view_form/model/group.py
@@ -88,7 +88,7 @@ class ModelRecordGroup(SignalEvent):
         self.load(ids)
         self.model_removed = []
         self.model_deleted = []
-        self.on_write = ''
+        self.on_write = set()
         self.readonly = readonly
         if self._context.get('_datetime'):
             self.readonly = True
@@ -130,12 +130,14 @@ class ModelRecordGroup(SignalEvent):
     def on_write_ids(self, ids):
         if not self.on_write:
             return False
-        try:
-            res = getattr(self.rpc, self.on_write)(ids, self.context)
-        except Exception, exception:
-            common.process_exception(exception, self.window)
-            return False
-        return res
+        res = []
+        for fnct in self.on_write:
+            try:
+                res += getattr(self.rpc, fnct)(ids, self.context)
+            except Exception, exception:
+                common.process_exception(exception, self.window)
+                return False
+        return list({}.fromkeys(res))
 
     def _load_for(self, values):
         if len(values)>10:
diff --git a/tryton/gui/window/view_form/screen/screen.py b/tryton/gui/window/view_form/screen/screen.py
index 5469f15917..8e31ce67ba 100644
--- a/tryton/gui/window/view_form/screen/screen.py
+++ b/tryton/gui/window/view_form/screen/screen.py
@@ -385,7 +385,7 @@ class Screen(SignalEvent):
         return position
 
     def set_on_write(self, func_name):
-        self.models.on_write = func_name
+        self.models.on_write.add(func_name)
 
     def cancel_current(self):
         if self.current_model: