Assign users to a category

I have been working on a WP website for my sons’ Cub Scout Pack (http://www.pack573.com). What I need is to hack the users DB and add a category field for each user. Then I want to limit their postings to that category.

So if I post, because I am the Cubmaster, I can post to all categories. However, my wife is only a Den Leader for the Wolves, so she could only post to the Wolves category. All ranks are children of the pack.

Events are a separate category. The pack has the lowest category id and the events is the highest.