Ribbon structure

[Anonymous]

I was wondering if there was a way to have elements of the ribbon(PushButtons, SplitButtons) continuously drop down or something similar. There are a lot of subcategories within subcategories that I would like to structure and looking at my options right now, it seems like I can only do two levels max (SplitButton containing a bunch of Pushbuttons) I'd like to have 3-5 levels.

[Anonymous]

To further explain my issue, I am looking to implement something like this..

Where Electrical has another SplitButton, and I would have possibly another two levels of cascading SplitButtons. I can't seem to replicate this as I can't add anything other than PushButtons to SplitButtons.