It should, I agree.  But it doesn't seem to be.  As noted with the links I provided, the orphaned reference problem is apparently known to exist.  Perhaps I should ask whether those TriPolys called up by the HitPoints are linked to the Mesh objects.  The Mesh objects are being overwritten, because of the loop structure (I can't think of any other way to iterate over multiple Meshes, sadly).  If there are still references in play for their elements, then something may be ending up orphaned.  I'll see if I can work out a way to test this idea.  Sorry to keep going on about it....  It's a frustrating puzzle, on my end.

I checked my code, and I don't see anything wrong with it, but that doesn't rule out error on my part fully.  The weights the .pyd is giving me are always either:

1.0, 0.0, 0.0

or

0.0, 1.0, 0.0

The third weight, which picks up the slack from the other two in the code, is always zero.  Which suggests that when the first two are being calculated, one is always set to 1.0 and the other to 0.0.  The higher value of these two seems to end up with 1.0, based on a quick glance at my results.  At any rate, in every single case, one of the tri vertices had a full 1.0 weight and the other two were zero.  This looks to me like the .pyd is offering the wrong results, because of the consistency of the results and the zero value for the third weight....

I've ported over my initial UV code, which doesn't do anything to handle seams or splits, and it works so far.  Having UV transfer integrated into the .pyd would be fantastic, of course, but I wonder if it might be premature, until and unless we can work out a way to handle the seams.  I had a couple of new thoughts to try for that, which probably won't work, but I'll test them anyway....

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.