It must be a bug.
I had repair my game, play with my vampire, go back to the world view, check on manage household and saw two new people in the "Not in World population" and they are vampire, plus there is this townie i have meet before, who wasn't a vampire, who came into forgotten hollow and when i click on her it says that she was a vampire, so i wait until she leave FH, and she is still a vampire.
I don't understand what my game is doing Oo'
Didn't touch my game, i locked my vampire in her house and wait, the game have create new vampire townie ( and i don't have any mod/cc in my game )