this is why time travel stories always make my head hurt...

I've been thinking about the ST:AOS timeline. Presumably it is like the TOS reality until the Kelvin is destroyed by Nero. But when I thought about that, how do the timetravel events work that have various future crews (from the regular timeline) interact with the past pre-split? Like how did the events of Star Trek: First Contact happen in the AOS reality? I mean, which version of the future characters have now ended up in the past? Or am I approaching this wrong? This makes my head hurt.