add subitems for the suit menu subitems(3 level tree)

Is it Possible to structure a  3 level tree with django-suit menu?
If yes how can I do this or if there is another way to customize in the menu.
what i need is something like that:

Main Menu|
                  |- SubItem1
                  |- SubItem2 |- SubItem2-1
                                     |- SubItem2-2
                  |- SubItem3