I'm not sure I properly answered this question posed in the title to the link below:

 

• How can Arcane be related to multiple people on different time lines?

So, in trying to answer this question I had to think about this and what I realized is that someone from say Earth's first timeline could travel time and visit the 2nd timeline and mate with someone in the 1st or 2nd timeline and then go back to their original timeline and then that child would be related to people in both timelines. This is theoretically possible.

However, as far as I know neither Arcane or Celeste Weaver were from different timelines

However, later on something like this happens because Ah Ray In is warned by Old Arcane not to go to Isfahel which allows young Arcane to actually marry Ah Ray IN even though Old Arcane is married to Ah Ray IN in her newest incarnation as Celeste Weaver.

So, this is one thing that can happen when time traveling goes on even along the same timeline when people's lives are drastically changed from one path to another.

So, Old Arcane stays married to Celeste Weaver because on his timeline Ah Ray IN became a martyred Saint and died.

But Young Arcane is saved from this fate by his Older Self who had to lose Ah Ray IN to Martyrdom.

So, as a direct result Young Arcane and Old Arcane have completely different lives as adults. Young Arcane becomes His Oneness of New Deva and Old Arcane joins the Galactic Time Guard and comes to earth and marries Ah Ray In's next incarnation Celeste Weaver.