This has been an issue for many years. Because of it I usually just stick to plasma packs or make single servings. I really wish that they would make it so non-vampires wouldn't automatically eat vampire food. Non vampire sims prefer plasma salad over other foods. I can have the fridge stocked but if there is any plasma fruit salad, they will eat it instead of the other food. Then they feel sick. Since it's been years I doubt this will ever be changed but I'm hoping to find a mod some day. I like playing vampires but it's a headache when they're in a family. It's similar to how vegetarian sims will eat meat autonomously. Such a strange thing to not address.
LOL yeah.
I used to have a household that was two vampires, a witch, and a mermaid. The vampires made a party size plasma fruit salad and the mermaid got into it, poor baby.
The mermaid also has the Child of the Ocean trait, so... I just micromanage his food.
