Forms 4.5 insert validation question

I'm rather new to Forms development an have a problem concerning input validation for detail records in a 2 block master-detail form which I just can't seem to find a solution for. So here goes:

A 2 block master-detail form (orginally generated using Designer/2000; the detail form is an interesection table, so its fields are not shown and are populated through an LOV from a lookup detailed table usage), the master block only shows a single record at a time and allows for query, insert, update and delete; the detail block also allows for query, insert, update and delete but shows 6 records at a time (populated through LOV). Now what I want to accomplish is that a newly created master record cannot be saved without there also being at least one related detail record being created. What's the best approach to take here? Any help is appreciated.

dave

-- 
David-Michael Lincke
Research Assistant
Institute for Information Management IWI-HSG, University of St. Gallen
EMail:	David-Michael.Lincke_at_iwi.unisg.ch, dlincke_at_bandon.unisg.ch
URL:	http://www-iwi.unisg.ch/about/team/dal.html