I am on the fence about adding more household slaves. One one hand, I like the idea of creating a real Ottoman Empire style harem for myself with plenty of concubines, but on the other hand, I don't really want this to turn into a full harem simulator with a villa that is packed full and overcrowded with defeated enemies and slaves. That would be a different kind of game than what we have now which is following the desert adventures of a Stalker and his down time at home. A bloated cast of characters can be difficult to handle and can quickly spiral out of control if a dev isn't careful.
I think a villa of this size is sufficient for the current family and a handful (perhaps half dozen) of slaves/servants but not too much more than that. I don't know. I haven't completely made up my mind on this point, but I am at least open to any possibilities that the dev team offer.