MegaMenu display only subcategories

Hiya. Currently looking at your megamenu extension.

Unfortunately any changes I make at the back-end of your demo are not visible in the front-end so I can’t figure out properly how it works.

Question is:
is it possible to create something like this (pardon my artistic skills)

https://ibb.co/mq2QeJ

e.g.
i have a category hierarchy like this

Microphones -- Types          -- etc.
Application   -- etc.
Brands         -- etc.
Accessories   -- etc.

I don’t want the first subcategory to be a clickable links but just Plain labels with subsubcategories listed underneath.

Also is it possible with your plugin to display items from different parent categories under the same main navigation button.

Thank you.