Why can't I add Sim to family?

"CursedDice;d-907743" wrote:
I have my Sim family and then started killing sims off. Now I'm down to the last two and only just saw now that the game has them as not brothers, but friends. I had to import one into CAS because you can't just create an identical twin for some reason, but there's no way to make them brothers. It just says can't edit pre-existing sim even with cas.fulleditmode on. They're not pre-existing, I made them.

i'm having something like that. im trying to remove a sim from the house hold and get them back into the household. i removed her now it wont let me add her back. can someone please help me? i tried everything to get rid of the at school thing when she's home. my sim : click all the spoilers to fix it.