By George I've got it!

This is Antonia's head together with a morph I made in Blender without ever using the "keep vertex order" button. I haven't written an .obj output function yet for my script, so haven't tested in Poser, but the two meshes shown here (via PolyScope) use the exact same face definitions, so if the vertex renumbering hadn't worked, we'd know it. :smile:

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