Just as a side note, if you don't make any keys for a bone you don't have to do manipulations after UpdateWorld, you can do then before with all your other code.
John, all you'd have to do is animate two meshes, hide one, animate both and read the rotations from the hidden one and use that to manually rotate the visible one.
John, all you'd have to do is animate two meshes, hide one, animate both and read the rotations from the hidden one and use that to manually rotate the visible one.