Navigation question

I’m electing to build a WP with fixed navigation as opposed to a drop-down menu — meaning, if a user were to select Member Directory they would land on a page where all of the sub categories for Member Directory are listed. You can see and example here.http://gtworkspace.com/otsego/member-directory-2

Things are navigating fine, however, when I select a sub category such as Auto, it will display the correct post but I loose my sub-directory. I can get it back if I put it in the index file, but that would put it there for every page and I’ll want something different for Galleries, Events, ect. Do I need to build an auto page, and if so, how would I navigate to it?