--- a/src/pyams_form/form.py	Tue Feb 20 11:17:52 2018 +0100
+++ b/src/pyams_form/form.py	Wed Mar 07 09:47:21 2018 +0100
@@ -173,19 +173,19 @@
         return result
 
     def update_content(self, content, data):
-        if self in data:
-            data = data[self]
-        changes = applyChanges(self, content, data)
+        changes = applyChanges(self, content, data.get(self, data))
         subforms = self.subforms + self.tabforms
         [subforms.extend(group.subforms) for group in self.groups]
         for subform in subforms:
+            if subform.mode == DISPLAY_MODE:
+                continue
             subform_update = ICustomUpdateSubForm(subform, None)
             if subform_update is not None:
-                updates = subform_update.update_content(content, data)
+                updates = subform_update.update_content(subform.getContent(), data.get(subform, data))
                 if isinstance(updates, dict):
                     changes.update(updates)
             else:
-                changes.update(applyChanges(subform, content, data))
+                changes.update(applyChanges(subform, subform.getContent(), data.get(subform, data)))
         return changes
 
     def render(self):
@@ -317,7 +317,7 @@
     def createAndAdd(self, data):
         registry = self.request.registry
         # create object
-        object = self.create(data)
+        object = self.create(data.get(self, data))
         if object is not None:
             registry.notify(ObjectCreatedEvent(object))
             # set parent temporarily to avoid NotYet exceptions
@@ -349,7 +349,7 @@
             form.updateWidgets()
             form.updateActions()
             form_data, form_errors = form.extractData()
-            data.update(form_data)
+            data[form] = form_data
             errors = errors + form_errors
         if errors or self.errors:
             return self.get_ajax_errors()
@@ -432,8 +432,6 @@
             self.actions['submit'].addClass('btn-primary')
 
     def applyChanges(self, data):
-        if self in data:
-            data = data[self]
         content = self.getContent()
         changes = self.update_content(content, data)
         if changes:
@@ -462,11 +460,7 @@
             return self.get_ajax_errors()
         # update form content
         try:
-            changes = {}
-            for form in self.forms:
-                if form.mode == DISPLAY_MODE:
-                    continue
-                changes.update(form.applyChanges(data) or {})
+            changes = self.applyChanges(data) or {}
         except ValidationError as error:
             # This error can occur with file-type inputs
             registry = self.request.registry