Merged Family always crashes after loading

I did search but couldn't see exactly the same situation/crash in other posts.

I played 2 sims through Uni as one household. They aged up/moved out of the dorms one after the other. I moved the first sim into an empty house, played for a little while, then went back to the neighborhood screen and added the second sim into the same house.
It loads into the household fine, then after a few live mode minutes it crashes without an error message. I've tried moving them out and back into the same house, as well as moving them to a new lot completely.
I can load and play townie households fine, it's just this one family.

I don't have any mods or CC. I've added The sims 2 folders to my antivirus exceptions. I've tried repairing the game in the EA app. I also tried backing up my save (the neighbourhoods folder in documents) before uninstalling and reinstalling the game, but I think I messed this up as I can't seem to restore my save.

I have the log from the original install/save.

Is there a way to avoid this bug in the future? If I start over and put 2 sims through uni again - how do I have them living together after uni without it causing issues?