User Profile Replication Engine: full replication of only certain accounts

I've configured the user profile replication engine to do incremental replication between two geographically separate farms and this works ok. But how can I replicate the profile info of all users that belong to a particular group?  Our two farms have been up and running awhile and so the users of each farm already have profile data. When I setup incremental replication it will only get NEW changes.  I can't do a full replication to or from the remote farm because each farm is the 'home' for a subset of users and a full replication would over-write the profile info on the destination farm.

I want to do a "partial-full" replication - ideally respecting the settings in the "trusted my site host locations", but we could base the replication on AD groups also.

Any Suggestions?   Thanks.

-John