If we are all recycled souls and souls make multiple journeys into bodies to achieve their tikun, which body/bodies get resurrected? Do souls get fractionalized and all bodies come back with part of a soul or does the whole soul come back in one of them? What is the source?
There isn’t one simple, all-encompassing rule for this. There are a number of situations which could produce slightly different results regarding this question. There are situations where multiple bodies that a soul was in during its various journeys down here will all return in techiyas hameisim and there are situations where only a certain body will be resurrected. One of the main factors has to do with whether the body in that lifetime was involved in sins that Chazal say there is no techiyas hameisim for. Another factor has to do with what body was the “ikar” regarding the overall tikun of that neshama. This is a deep and complex calculation. See Rav Chaim Vital – Shaar Hagilgulim Hakdamah 11.