Wow. The HellBorn, author of the all time most downloaded Renderosity freestuff? Welcome back. :) Compose already does what you want - as does the Poser export process as described by PhilC, but I find that more laborious. However to answer your question, as far as I know you need to make sure that the vertices in your export are in the same order as they were in the original geometry file. If the group in question is fragmented in the vertex list, you can (indeed, should) omit the vertices which belong to groups other than the one you're exporting. Hope that helps.