I don't know if feeding from a sim affects celebrity vampires in TS3 but without mods, there's no way to drink without permission or turn a sim without permission. Also you get a penalty for being a celebrity occult and woohooing with literally anyone. Just turn off the celebrity system is what I'm saying! The vampires are fine. If you have Supernatural, there's a cute interaction to enthuse about the joys of plasma or whatever with another vampire, but it ends in them toasting their plasma packs, which is the cute part.