Just save your game under a new name and try on that.
Backups are very good to though, so also backup your saves folder and other stuff that's important to you
First results: switched from one family to another, played 24 in-game hours, switched back - all acquaintances were gone, only relatives and friends left. I will test further.
EDIT: I couldn't recreate the bug with disappearing friends. I played with third family for several in-game days, but all friends remained. Not sure what caused this earlier and if this is the same bug or different.
Well that's good to hear.
I mean, even if we're not liking the changes, at least it's not bugged :D
