Re: Mapping problem, need ideas please.

You are trying to implement a grouping pattern. You might like to check out Muenchian grouping 
http://blogs.msdn.com/chrisromp/archive/2008/07/31/muenchian-grouping-and-sorting-in-biztalk-maps.aspx
http://www.richardhallgren.com/efficient-grouping-and-debatching-of-big-files-using-biztalk-2006/