I've had some time for this info to sink in an now I have a question: I assume that you make copies of the head once you cut it off and before you combine and merge it back onto the body. Why is it important that the head vertexs be renumbered with the lower numbers and the body be numbered with the higher vertex numbers. What does this do for you?

Won't the blend shaped have different vertex numbers than the head once the head is renumbered?