Hide/Show MDI Child forms when Ribbon Tab is changed

I am using a Ribbon Control on a MDI Parent Form in my desktop application.  I would like to perform a ribbonTab1_ActiveChanged event that hides specific MDI Child formsonly if they are open and shows specific MDI Child formsonly if they are hidden.

Example: Lets say I have 3 MDI Child forms open while in ribbonTab1.  When I select ribbonTab2, I would like the 3 Child forms to hide.  While in Ribbon Tab2, let say I decide to open 2 MDI Child forms.  When I return back to ribbonTab1, I would like to hide the 2 Child forms and show once again the 3 hidden Child forms in ribbonTab1.  I would like each ribbonTab to only show the Child Forms that were opened while in that ribbonTab.  Any help would be greatly appreciated. Thanks in advance!