Me, too, Les.  I think I'm getting depressed about it again.

But I was able to get the modified twin parenting to work.  Trick was putting an explicit "inkey parent" in the cr2.  At that point, the hierarchy editor allowed me to drag the parts on to that prop.  So far, though, I can't get Poser to set up that relationship just from the data in one cr2; it seems to require that I manually go into the hierarchy editor to finish the operation.

Since I was mucking about with figure hierarchy, by the way, I created a clone figure with only two physical body parts (but a complete cr2), and parented the "real" figure to it.  Unfortunately, although that worked great for imposing my new IK motions, it meant that the built-in JCMs no longer worked.