Board Thread:Theories and Speculation/@comment-32617252-20180317055942/@comment-734582-20180319135446

Mrsunrider wrote: What I wanna know is if (when) Sarada's eyes are unlocked, who'd be a good candidate for her? Would Sasuke be a candidate or would his Rinnegan make him only half-eligible? Sasuke's old eyes are probably still around. Lorenzo.r.2nd wrote: well, from what we have seen, only siblings, who have the closest dna to ur own, can trade eyes and actually get an ems, so it prolly wont work with sasuke and sarada. Sarada has half his DNA, so it seems fine to me.

JamesDuh wrote: But if there's a special connection like being blood related, a unique evolution occurs. That's probably why you don't see an EMS retain the other person's abilities. We have no idea what's actually going on with the EMS though. It could be the combined trauma and pain of a sibling offering his eyes in death create a second MS awakening, which overwrites the donor's MS powers. Without more information on the EMS, there's no real way to know.

We do know however that the power of MS is finite (e.g. Madara had a transplanted basic Sharingan, didn't get a new MS or EMS. Same with Obito), so i think it would be weird if the MS could be swapped and somehow gain more power in this exchange.