Uh, that isn't what she says?
Ok, but doesn't every single time travel movie work this way?
"We have to do back in time to do X, and we run into ourselves"
I don't see how that is enough to show that all the "timelines" exist as seperate things
We wouldn't scale, say, Back to the Future to Multiversal, would we? Maybe we would, just nobody would scale to it
Isn't this just her saying "Since I am from the future, and I have it in the future, I can travel back here from any point, because the Burrow exists outside of time"?
She says this because the Monarch guy asks "How were you able to come here"
Though to be fair, if the timelines didn't exist seperately, then I don't know how she would still have it in the future, but I havent seen the show