Maybe. Maybe all these timelines, countless JFK timelines among them, just exist, and time is just your perception as you travel along them. And perhaps you can go and follow anyone of them. Like a library with infinitely many books to read, each with infinitely many versions.

You could go be Adolf Hitler, and know what if feels like to be consumed by hatred from within. And perhaps you live it again and you could branch in an entirely different direction in which Adolf becomes a famous humanitarian instead of an historical monster? And perhaps you could learn something from the difference.

That is the whole point of those two links I sent you. All timelines branch countless times in countless directions, again and again and again, ad infinitum. And if consciousness can move through the sixth dimension, then you can go move through time and follow any one you choose. If so, with all that to choose from, do you still think your soul, free of the baggage of it's human mind, will say "I want to come back as my brother?"