With a new pack about legacy I'm expecting some kind of update dealing with families, I really hope for one at least. I play multiple households over several generations and the game won't acknowledge that my original Sims great grandchildren are related, it gets a bit uncomfortable when they start flirting.
I follow each of the original sim's children and then their children and so on, I know the family connections but they don't. I don't expect them to let us have details going back twenty generations but at least having a few more would do wonders.
Also REALLY need the premades family trees fixed, Malcolm Landgrabb won't stop flirting with Johnny and I don't like it, I had to cheat them into siblings. They've basically confirmed multiple times that Nancy is their shared mother, someone really needs to let those Sims know.