As promised, I ran the experiment ... and learned a lot, not least of which was, don't make assumptions! Suuuure, you can swap skinmaps between Michael 4 and Victoria 4.2, and make a real mess, and have a lot of fun with primitive humor (which was the force driving these renders), so I'd assumed that you'd be able to slap the M4 skinmap on Michael 3, and though it wouldn't fit, it'd be good for a laugh. Right? Actually, wrong.
The truth is, there doesn't seem to be any retrocompatibility whatsoever! While you can trade skinmaps between male and female models which share the same generation geometry, but go back a generation to M3, and you're right out of luck.
Well,no great loss, really. Having had a muck about with the M3 model today, I can honestly say, I'm somewhat glad I didn't get into this kind of artwork a few years ago, because M3 is about as realistic as a tailor's dummy. I'd have been quite disappointed with the results, rather than being inspired to learn!
So there you are -- all questions answered about Michael 3 and his compatibility (or lack thereof) with Michael 4. As the post title says, they're not exactly siblings.
Jade, 24 May