I have a member database with a yes/no field which when set to yes displays a subform where the group or groups which the member belongs to can be selected from a list. I need to make sure that if a member ceases to belong to a group the checkbox cannot be turned off until after a message box is displayed and action taken to remove them from the list of groups.
Is there a way of doing this with VBA.

The current vba for the yes/no checkbox is as follows:

Private Sub Form_Current()

    MemberGroupSubF.Visible = GroupLeader

End Sub

Private Sub GroupLeader_AfterUpdate()

If GroupLeader Then
        MemberGroupSubF.Visible = True
        
            MsgBox "Select All The Groups for which this Member is Leader:" & vbNewLine & " " & vbNewLine & _
                "You can also De-Select a Group's Name by Selecting the Row and Pressing Delete on the Keyboard", vbInformation, "Group Leader Selection"
    
    Else
        MemberGroupSubF.Visible = False
End If

End Sub