Do you currently have the other female (hahahaha! the "other" woman!) on hand or are you looking at getting another? My only concern would be possible disease/illness transmission if you're introducing a new female to the ones you already have. If you already have a female that has been around the male/female pair you currently have, there shouldn't be any issues putting all three (or more) together. Don't mean to complicate the issue, just saying... Anyway, there shouldn't be any issues with introducing another female to the mix provided everyone is healthy.