I've had two females and a male go in at the same time before. I dragged the guy over to the female and at the same time there happened to be a second one standing right next to her and *smooch* they all went in together. As far as having more couples go in at once, if you make several breeders or breed several males and females at nearly the same time. There's a great chance they get it on *cringe* at the same time. XD