Well, since I first wrote, I have seen the "smart prop prompt" again. If I accidentally try to save the non-parent part of the complex prop (i.e., Rplate in the example above), Poser sees that Rplate has a parent (the shaft) and asks if I want to make it a smart prop. But it still won't ask the smart prop question of a prop whose parent is part of a figure, and of course, it's almost always figures we want to smart prop to. (And I know perfectly well that people smart prop to them every day. And maybe I have, without the prompt. So . . . "smart prop prompt" has not completely vanished from the scene, but I'm still asking all my original questions.)