Frank,
Are you trying to retrieve information from multiple tables into one Business Object?
If so Have you tried using BO’s that are based on views? I’m doing this for some of my reports and its working fine. When I’m working with Updateable data I just setup BO’s with parent – child relationships so that when Parent A retrieves data child B goes out and retrieves the appropriate row via HookParentRetrieved() or HookParentNavigated().