I would add a form method and call this code from the Click(), InteractiveChange() or Valid() event of the optiongroups.
e.g.,

** opgOne.Click() And opgTwo.Click()
Myform.MyMethod()

** Myform.MyMethod()
lnOneVal = this.opgOne.Value
lnTwoVal = this.opgTwo.Value

Do Case
 Case lnOneVal = 1 And lnTwoVal = 1
   ** whatever happens here, e.g.
   this.txtOne.Enabled = .T.
   this.txtTwo.Enabled = .F.

 Case etc.
  etc.

EndCase