True but I get the impression she didn’t want him seeing his son at all. That maybe true for ships back then but he could still visit him during leave etc.

No mention of Spock’s sister during all of this. Goes with my theory that she’s one of the alien parasites from Rick and Morty.
That explains it. I’ve still haven’t seen all of the TAS episodes. That show used to creep me out when I was younger for some reason.The only canon mention of Joanna McCoy was in the TAS episode The Survivor, so if you're not familiar with TAS that might be why you weren't aware of her. I think there have been at least two or three different versions of her in the books and comics over the years.

No mention of Spock’s sister during all of this. Goes with my theory that she’s one of the alien parasites from Rick and Morty.