IF the portals on on the tabs, then only one portal is visible at a time. You can either define a relationship that matches only to the desired set of records or define different portal filter expressions for each portal.
obviously the entire tab control is an object.
Actually, each panel in the tab control is an object and can be given a different object name in the name box of the inspector (position tab).
If the portal is not in the tab control, you can use OnObjectModify on the tab control and use GetLayoutObjectAttribute to determine which panel is now the front tab panel. This requires giving each tab panel a different object name in the inspector.
Thanks, I didn't seem to understand tab controls like I thought. After reviewing this portion of "The Missing Manual" I think I fixed my problem.
And thanks for clarifying the object piece. That makes sense now.