Hi Mel:

Why not specify the value of thisform.cNavWorkarea to the child form's workarea/alias when you activate the child form. Remember that when you do this, the controls will need to be refreshed. In the child form's Activate method have something like :-

thisform.cNavWorkarea = 'ChildWorkArea'
thisform.oStateManager.RefreshAll('Form')   && Parameter will refresh form related actions.

When you re-activate the parent form, you will have to "reverse" this logic.

HTH