Sims 2 Apartment Life Question?

Within my game, I've made four different families and moved them all into the same apartment unit. I later moved one family out into a completely different house, but when I went to play on the apartment unit again, I found that the family was still walking around on the lot, but had no home to go into. This lead to all their needs going to hell, and them becoming so sick to the point that they were infecting every other sim that came out of their apartment unit. So, my question is, has anyone else had this problem and does anyone know how to permanently remove the family from the lot without killing them off or affecting them when they're on their separate lot.