RJ, I ran into this problem in the Clan Douglas Dynasty as well. One day I had another family member group up with the ghost and they went to Central Park. At that point, I wasn't trying to get the ghost back in his urn, I just wanted to give him something to do. When the living sim came home, I couldn't figure out how to get the ghost to come so I just left him to find his own way home. Later that evening I checked his urn and found he was in it. I then moved it to the family graveyard on another lot. I kind of liked having him around, but as you say, it was disruptive to the sleep of the living sims.