Groups: Category inside Category? If so how?

Hi Si Team

I currently have 2 Categories:

“Start here.” Which is the group that people get put in when they join the site.

http://finalbug.net/groups/3-start-here?ordering=latest

I have 2 further groups in the category “Webinars.”

http://finalbug.net/groups/item/17-learn-fcpx
http://finalbug.net/groups/item/18-learn-resolve

I am wondering if I can put a category inside a category?
i.e. “Webinars” inside “Start here”?

Please advise


Paul