diff --git a/addons/base_calendar/base_calendar.py b/addons/base_calendar/base_calendar.py
index f95b8fb19c7..9cf07a4b73e 100644
--- a/addons/base_calendar/base_calendar.py
+++ b/addons/base_calendar/base_calendar.py
@@ -88,6 +88,16 @@ def base_calendar_id2real_id(base_calendar_id=None, with_date=False):
 
     return base_calendar_id and int(base_calendar_id) or base_calendar_id
 
+def get_real_ids(ids):
+    if isinstance(ids, (str, int, long)):
+        return base_calendar_id2real_id(ids)
+
+    if isinstance(ids, (list, tuple)):
+        res = []
+        for id in ids:
+            res.append(base_calendar_id2real_id(id))
+        return res
+
 def real_id2base_calendar_id(real_id, recurrent_date):
     """
     Convert a real event id (type int) into a "virtual/recurring event id" (type string).
@@ -1328,16 +1338,6 @@ rule or repeating pattern of time to exclude from the recurring rule."),
             data['end_type'] = 'end_date'
         return data
 
-    def remove_virtual_id(self, ids):
-        if isinstance(ids, (str, int, long)):
-            return base_calendar_id2real_id(ids)
-
-        if isinstance(ids, (list, tuple)):
-            res = []
-            for id in ids:
-                res.append(base_calendar_id2real_id(id))
-            return res
-
     def search(self, cr, uid, args, offset=0, limit=0, order=None, context=None, count=False):
         context = context or {}
         args_without_date = []
@@ -1387,6 +1387,13 @@ rule or repeating pattern of time to exclude from the recurring rule."),
                 return True
 
     def write(self, cr, uid, ids, vals, context=None, check=True, update_check=True):
+        def _only_changes_to_apply_on_real_ids(field_names):
+            ''' return True if changes are only to be made on the real ids'''
+            for field in field_names:
+                if field not in ['message_follower_ids']:
+                    return False
+            return True
+
         context = context or {}
         if isinstance(ids, (str, int, long)):
             ids = [ids]
@@ -1398,7 +1405,11 @@ rule or repeating pattern of time to exclude from the recurring rule."),
                 continue
             ids.remove(event_id)
             real_event_id = base_calendar_id2real_id(event_id)
-            if not vals.get('recurrency', True):
+
+            # if we are setting the recurrency flag to False or if we are only changing fields that
+            # should be only updated on the real ID and not on the virtual (like message_follower_ids):
+            # then set real ids to be updated.
+            if not vals.get('recurrency', True) or _only_changes_to_apply_on_real_ids(vals.keys()):
                 ids.append(real_event_id)
                 continue
 
@@ -1414,7 +1425,9 @@ rule or repeating pattern of time to exclude from the recurring rule."),
                     rrule='',
                     recurrency=False,
                 )
-
+                #do not copy the id
+                if data.get('id'):
+                    del(data['id'])
                 new_id = self.copy(cr, uid, real_event_id, default=data, context=context)
 
                 date_new = event_id.split('-')[1]
@@ -1507,7 +1520,7 @@ rule or repeating pattern of time to exclude from the recurring rule."),
 
         for r in result:
             for k in EXTRAFIELDS:
-                if (k in r) and ((not fields) or (k not in fields)):
+                if (k in r) and (fields and (k not in fields)):
                     del r[k]
         if isinstance(ids, (str, int, long)):
             return result and result[0] or False
diff --git a/addons/base_calendar/crm_meeting.py b/addons/base_calendar/crm_meeting.py
index 80d50e8a1df..8e4ab2341ab 100644
--- a/addons/base_calendar/crm_meeting.py
+++ b/addons/base_calendar/crm_meeting.py
@@ -23,9 +23,8 @@ from osv import osv, fields
 import tools
 from tools.translate import _
 
-import base_calendar
+from base_calendar import get_real_ids, base_calendar_id2real_id
 from base_status.base_state import base_state
-
 #
 # crm.meeting is defined here so that it may be used by modules other than crm,
 # without forcing the installation of crm.
@@ -69,7 +68,7 @@ class crm_meeting(base_state, osv.Model):
     def message_get_subscription_data(self, cr, uid, ids, context=None):
         res = {}
         for virtual_id in ids:
-            real_id = base_calendar.base_calendar_id2real_id(virtual_id)
+            real_id = base_calendar_id2real_id(virtual_id)
             result = super(crm_meeting, self).message_get_subscription_data(cr, uid, [real_id], context=context)
             res[virtual_id] = result[real_id]
         return res
@@ -128,7 +127,7 @@ class crm_meeting(base_state, osv.Model):
                         subtype=None, parent_id=False, attachments=None, context=None, **kwargs):
         cal_event_pool = self.pool.get('calendar.event')
         if isinstance(thread_id, str):
-            thread_id = cal_event_pool.remove_virtual_id(thread_id)
+            thread_id = get_real_ids(thread_id)
         return super(crm_meeting, self).message_post(cr, uid, thread_id, body=body, subject=subject, type=type, subtype=subtype, parent_id=parent_id, attachments=attachments, context=context, **kwargs)
 
 class mail_message(osv.osv):
@@ -138,11 +137,9 @@ class mail_message(osv.osv):
         '''
         convert the search on real ids in the case it was asked on virtual ids, then call super()
         '''
-        cal_event_pool = self.pool.get('calendar.event')
         for index in range(len(args)):
-            if args[index][0] == "res_id":
-                if isinstance(args[index][2], (str)):
-                    args[index][2] = cal_event_pool.remove_virtual_id(args[index][2])
+            if args[index][0] == "res_id" and isinstance(args[index][2], (str)):
+                args[index][2] = get_real_ids(args[index][2])
         return super(mail_message, self).search(cr, uid, args, offset, limit, order, context, count=False)
 
 class ir_attachment(osv.osv):
@@ -152,10 +149,27 @@ class ir_attachment(osv.osv):
         '''
         convert the search on real ids in the case it was asked on virtual ids, then call super()
         '''
-        cal_event_pool = self.pool.get('calendar.event')
         for index in range(len(args)):
-            if args[index][0] == "res_id":
-                if isinstance(args[index][2], (str)):
-                    args[index][2] = cal_event_pool.remove_virtual_id(args[index][2])
+            if args[index][0] == "res_id" and isinstance(args[index][2], (str)):
+                args[index][2] = get_real_ids(args[index][2])
         return super(ir_attachment, self).search(cr, uid, args, offset, limit, order, context, count=False)
 
+    def write(self, cr, uid, ids, vals, context=None):
+        '''
+        when posting an attachment (new or not), convert the virtual ids in real ids.
+        '''
+        if isinstance(vals.get('res_id'), str):
+            vals['res_id'] = get_real_ids(vals.get('res_id'))
+        return super(ir_attachment, self).write(cr, uid, ids, vals, context)
+
+class invite_wizard(osv.osv_memory):
+    _inherit = 'mail.wizard.invite'
+
+    def default_get(self, cr, uid, fields, context=None):
+        '''
+        in case someone clicked on 'invite others' wizard in the followers widget, transform virtual ids in real ids
+        '''
+        result = super(invite_wizard, self).default_get(cr, uid, fields, context=context)
+        if 'res_id' in result:
+            result['res_id'] = get_real_ids(result['res_id'])
+        return result