Customer master - parent billing type

Is there a mechanism for preventing users from adding the customer parent as a sold to or ship to address book record during sales order entry?  Billing type (BADT) would seem to be designed for that  purpose.  However, the standard UDC only allows the csutomer record to be defined as  Bill To, Ship To, Bill To or Ship To, or Inactive - not "Neither Ship To or Sold To".  Any alternative approaches would be appreciated.