Mary,
Interesting question and perfect timing. I just recently published an add-in for creating mutually exclusive option buttons in Word. It appears that it is really option buttons that you want. You want the user to be able to select either yes or no but
not both and if yes is check then you want them to check A, B, C or D no?
Using the following add-in you can create the two groups of option buttons.
http://gregmaxey.mvps.org/word_tip_pages/mutually_exclusive_content_control_option_buttons.html
Assuming that you tag the Yes\No group as 1 and the ABCD group as 2, then adding the following code in the document's ThisDocument module should give you the results you need:
'Add these lines immediately after the Dim bRecheck as Boolean statement in the Sub Document_ContentControlOnChange procedure.
If ActiveDocument.SelectContentControlsByTag("optGrp1_M_2").Item(1).Checked Then
ActiveDocument.SelectContentControlsByTag("optGrp2_O_1").Item(1).Checked = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_2").Item(1).Checked = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_3").Item(1).Checked = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_4").Item(1).Checked = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_1").Item(1).LockContents = True
ActiveDocument.SelectContentControlsByTag("optGrp2_O_2").Item(1).LockContents = True
ActiveDocument.SelectContentControlsByTag("optGrp2_O_3").Item(1).LockContents = True
ActiveDocument.SelectContentControlsByTag("optGrp2_O_4").Item(1).LockContents = True
Else
ActiveDocument.SelectContentControlsByTag("optGrp2_O_1").Item(1).LockContents = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_2").Item(1).LockContents = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_3").Item(1).LockContents = False
ActiveDocument.SelectContentControlsByTag("optGrp2_O_4").Item(1).LockContents = False
End If
I've put a working example in dropbox: https://dl.dropboxusercontent.com/u/64545773/Demo%20Option%20Buttons.docm