Can ghost sims be converted to Vampire?

You probably can. First you need a spellcaster to bring the ghost back to life. Then have a vampire turn them. I brought Mimsy back to life at the Von Haunt Estate. After that she was just a "not in world" Sim.

"Arzekial;c-17294874" wrote:
You probably can. First you need a spellcaster to bring the ghost back to life. Then have a vampire turn them. I brought Mimsy back to life at the Von Haunt Estate. After that she was just a "not in world" Sim.

But you definitely cant convert them when they are still a ghost?

As a ghost, no, they can't be turned into a vampire. To do that would require cheats.

I'm not really sure, I'm just now experimenting with vampires

Have a sim get bit. They get the debuff saying they will turn in a few days I think it is. (It might only be hours, I don't quite remember how long it lasts). Kill that sim while the buff is active. They should still turn vampire after becoming at ghost. It happened to me purely on accident but it works. ;) The vampire can't bite the sim as a ghost because ghosts don't have plasma. Of course you can also just kill a vampire to get the ghost but if you're looking to see the ghost animation turn vampire, the only way to do it without a mod would be to have the sim die after being bitten.