HABTM check box for three models

This is the sort of question you should post to the regular Rails email list, not here. This core list is about development of the framework, not how to use it. That said, you should drop the multiple habtms and look at creating a threeway join model, something like a Capability that represents the right concept as a concrete entity.

You should now take this to rubyonrails-talk@googlegroups.com