My personal experience with FBX and Poser and rigging is that you can only pose the individual parts of a figure manually. Furthermore, when importing a rigged compound FBX figure, Look at the Hierarchy window, and use the topmost FBX figure to pose all the “conformed” figures appearing below it. This may even be Teeth or Pants, but so long as it appears as the topmost of the hierarchy window list, that’s the one to use for posing. Finally, if you have zero pose in frame 1 and a different pose in say frame 30, Poser does not pose the figure in the frames in-between. I find that the pose in frane 1 is the same all the way through to frame 29, and then frame 30 gets the different pose. No tweening or interpolation of poses.

Eternal Hobbyist