ECB custom action sub menu (server side programming)

Hi,

I'd like to add a custom actions to a list ECB menu. I'm currently able to add them server side with this code :

                var menuAction = list.UserCustomActions.Add();
                menuAction.Name = "MyActionName";
                menuAction.Location = "EditControlBlock";
                menuAction.Sequence = 450;
                menuAction.Title = "MyTitle";
                menuAction.Url = "MyAction";
                menuAction.Rights = SPBasePermissions.EditListItems;
                menuAction.Update();

Now I'd like to group my items in a sub menu (like the "Send To" menu)... Is it possible to do that server side (I cannot use client side model for this task)?