General Discussion

I can't, however, accept that a point in space "includes" time.
Yes, it's a 4th dimension per Einstein, but with exceptions like Feynmann, time is a marker of where that 3 dimensional coordinate was when the 4th axis was at z'. That 3 dimensional point is at a different set of coordinates in 3 dimensions, but it still exists independent of time.
The 4 dimensional coordinates differ too, but the xyz is directly correlated to time, because distance traveled is velocity time. So, as in simple algebra, time cancels out.
I suppose the tricky part is that time us not a constant as gravity causes curvature in space that won't be the same at a point in the future, and since the source of that gravity has moved, the curvature of space is reduced or even non-existent.
Since time slows down in regions of low curvature, time isn't a constant.
So, we're back to "extraordinarily" difficult & unlikely to occupy the same spot in 2 tines, but not impossible.
I have issues of time travel forward too, because it's traveling into nothingness unless, also like Feynmann, we believe the outcomes are determinate. That smacks too much of predestination which I can't accept.
So, as far as I understand it, only time travel into the past is allowable and only to a period before one was born. Otherwise we're back to places at the same time and the "where'd the extra matter come from" question raises its head.
Fun conversation! Thanks