Oh good to know. I don't think I've paired two different occults together. I usually pair them with human Sims because I like the gameplay of trying to restore one to human or make the other occult.
I guess adoption is the best option for Vampire/Mermaid/Spellcaster/Alien couples who want babies. There are lots of orphaned human baby Sims that need good homes lol. I'm adding this to my list of things to do in the game. I think it would be fun gameplay to have human Sim kids get adopted into a home of Vampires and Spellcasters. :lol: