PS: Instead of exporting the welded subd-0 mesh, I could in principle also use a small Poser Python script that derives the mapping between vertex numbers in the unwelded and welded mesh (there's a function in OBJ_ImExport for that that I could borrow) and writes that out into a file.

But unless I get stuck with my implementation, I'd rather not do that because having to use two script, one inside and one outside of Poser, just makes things even more awkward I feel.

-- I'm not mad at you, just Westphalian.