Problem fixed somehow! I finally re-generated all the Business Objects for the parent/child tables (using Dynamic SQL statements), re-added my custom rules and Voila! Everything works now! I don't know about the issue with calling SP's with parameters because I am now using Dynamic SQL statments except for retrieving child records. I never figured out where the erroneous child updates were coming from since they somehow by-passed the child business object classes including the rule checking.