>>40659768 (OP)No, the past doesn't exist anymore.
But, have you thought about why are they called "timelines"? It's because they're literally lines, at least conceptually, there are lines that are identical to our own, but shifted in time, so "the past" is still happening there.
You can reincarnate in the past on a different line, and someone in a future line can reincarnate in their past in our line.
But doing so means you're now able to stop your own birth, so you are never born to travel back in time to stop yourself from being born.
This would create a series of alternating lines where you are only born in half of the lines.
And that's why you can't overlap with yourself (but you could overlap with a self that was born on a different line.)