by Mike Churchward.
Hi Joe -
You should check out the ELIS add-ons. One of its major features is "usersets", which is a hierarchical organizational structure that can be applied to your user base and used for many different purposes such as enrolment management, reporting, etc.
ELIS can be found here: https://github.com/remotelearner
Documentation on usersets can be found here: http://rlcommunity.remote-learner.net/mod/book/view.php?id=63&chapterid=657
mike