My girlfriends two kids are moving in with us but I don't want them to

My girlfriend and i are both unemployed and we live together. Her Mom has been taking care of her two kids for the past 2 years but is now saying no more. So they gotta move in with us. But we don't set a very good example-partying and my roommate smokes in the house and my dogs don't like little kids so I told her she shouldn't move them in. But she can't move out cuz she has no job. I told her to send the kids to their Dad but she doesn't want them that far away. She is pregnant with my kid so it is gonna get real crowded real soon. What should I do/