I just saved one sim from Grim after she collapsed from freezing. She was on the street in front of my sim's house and my sim convinced her to group up. It would take too long to walk back to my sim...
@KatzMeowz are you still reading this thread? You seem to have this problem in a big way and stated you have never installed any mods. Your saves could be useful to the guru asking for submissions.
@Tanja1986 if you are playing a vanilla game your saves would likewise be helpful!