Specific Page Widget for Each Silo

I am looking for a solution to designing a siloed website with WordPress.

I want to have 5 silos based each devoted to one topic with 6 to 10 pages per silo.

What is needed is a way to have all pages WITHIN the silo linked together. That is, a sidebar or menu that has all the pages in the silo linked with a page widget or similar tool. The standard “Pages” widget will of course list ALL the pages in the site which is what I do not want.

What is important is if I add a page or multiple pages within one of the silos, that new page is now in the menu or sidebar for that one silo and not any of the others.

Similarly, I want to have a footer that is specific to each silo as well with similar capability of cross linking the pages within that silo.

So, specifically:

5 silos that cross link WITHIN the silo only
5 separate footers (one for each silo)

The question is what is the best way to handle this? Can WP do this out of the box? Does it require template editing? Are there plugins that have this functionality?

Thanks all for the help!

PVB