MS Access linking subforms

[rdr]

Hi,
I have a form with several subforms, each of the subforms on a separate page of a tab control.
Some of the subforms have to be linked to the main form using one child/master field; some of the subforms - using three child/master fields.
I am trying to change the number of the fields to be linked when the TabContron is changed:

Private Sub TabCtl_Change()
Select Case TabCtl
Case 0, 1, 4
TabCtrlSubForm.SourceObject = TabCtl.Pages(TabCtl).Tag
TabCtrlSubForm.LinkMasterFields = "lstTeachers;txtCN;txtON"
TabCtrlSubForm.LinkChildFields = "Id number;Custom Number;OccupNo"
Case 2, 3, 5, 6, 7
TabCtrlSubForm.SourceObject = TabCtl.Pages(TabCtl).Tag
TabCtrlSubForm.LinkMasterFields = "lstTeachers"
TabCtrlSubForm.LinkChildFields = "Id number"
End Select
End Sub

But it is not working - the form still "remembers" the previous number of fields and does not switch to the new one.
Does anyone have an idea if this is possible to be done, and if yes, which is the proper event?

Thanks a lot,
Radosveta Drakeva