[Zope] Object Manager Product Dev Question

I am trying to make a folderish ObjectManager that can display items that exist inside it (in ZODB) as well as some items in a db. I would like the database items to appears as if they exist in the folder. Most of this is for the manage interface. I created a Product that extends ObjectManager. Should I just override objectItems and objectIds? But I am worried about how to handle the _getObj method. Any suggestions? Chris