Something do to with school/teens, maybe going to high school will be a playable activity. More things for teens to do, like groups and activities only available for teens.
I can't get the option to come up either. The ghosts in question lived at the lot before they died but my Sim did not. The prior residents died in a fire while my Sim was visiting. My Sim liked their house and since it was available to buy after they died, she did and the ghosts came with the house. My Sims is close…