Is there a cheat that turns a ghost into a living solid sim?
I added a family to my game, from the gallery, and part of this family are ghost. I left them this way to keep the family connection intact. The problem with this is they don't have tombstones, and ...
I don't know about cheats, but you can make Ambrosia to revive your ghost sims. If you have Romantic Garden Stuff I think you can use the wishing well too.