I'm having just a bit of difficulty grasping how to combine figures to create a new figure. Suppose I wanted to put a lion's head on a horse, or make a centaur, or a two-headed camel! I import two poser figures, and try to re-arrange parts from both figures in the hierarchy editor - but if I drag anything from one figure to the other, Poser hangs. Any clues on what I'm doing wrong?