(1) Here below the original soul does not leave the body. Rather, the two souls are present at one and the same time – whereas in the upper realm the ascending Partzuf gives its original interior to the Partzuf beneath it while itself rising up to receive a different interior.
(2) This leads to a further difficulty. Here below it is truly no problem if the body does not change. It simply stays as it was with the first soul, which does not leave it. However in the upper realm it would appear that there would have to be some change in the exterior. Since the Partzuf in question receives a new, different interior, should it not also receive a new exterior?