What you wrote sounds fine.
Having a sort of "root" object where List fields contain Odds and Ends, and some rules rely on Odds (but not Ends) being updated and others that don't it's not a good approach to make root a pattern in each rule.
It's like information hiding: A rule working with Odds should not have access to Ends.
A frequently given advice is: insert List elements as facts and reason with them if they represent independent entities. If necessary, locate siblings via a "parent" pointer.
-W