I honestly don't think you can make different Timelines more complicated than they are right now.

I'll tell you what's complicated, trying to work out the implications of Bill Wyman (ex Rolling Stone) marrying an 18yr old Mandy and his son then marrying Mandy's mother.

(This never happened in my reality so it's a type of thought experiment like Schroedinger's Kat)

So Bill gets married to Mandy and has a new son, which makes his own oldson (married to Mandy'd Mother) the new son's Father-in law, Grandad and brother

Now the old son has a new newson with the mother. This Makes Bill a GrandDad and Brother-inlaw and his wife is his grandsons sister
His wife is also her own mothers, Mother-in law. The Mother is Bill's Mother-inlaw and Daughter-in law.
The Mother is also a Granny to Bills child and the child is an nephew to his Brothers child who has Bill as his GrandDad and Brother-in law.
I gave up about here.
I will let someone else untangle this family mess. Have fun!

Now that is complicated;D~