Yes you can have alien vampires; I have one of them. I also have a vampire ghost. I got the vampire ghost after my vampire died in the sun and the newer Sims had them join the family I started playing. Keep in mind I only started game with the one vampire in play that's now a ghost. But after that they went on vacation with the vampire / ghost 3 vampire Sims 1 alein Sim a toddler with a alein dad and vampire mother. During that time the vampire / ghost went to the hidden vacation spot to harvest tomorrow planto. When I got back with the Vampire / ghost I noticed one of my male vampires was abduct that could have happend while I was on the lot and did not notice aliens and Pregnant. So I just had the baby with that male Sim. When the baby was born it was blue with black hair and when aged up the baby was wearing human clothes. It was a - known alein - but when the baby became a teen the baby turned into a vampire. Most likely being the earliest time to turn in to a vampire. So now the teen is a vampire with the power of both alein vampire. I have used both powers. Even grow that alein vampire up and had it have a baby. That new baby is a alein and now a toddler in a alein diaper. So I think it is going to be alein when full grown. But with the mother I am unsure if all babies form this point will be either alein or vampire still testing it. But yes you can have alein vampire sim.
