Was the mother of the baby there when this happened? If I were that mother, I would not want my child to be in daycare with those two girls. The baby is in danger, not only physically, but also emotionally. It will be very hard for you to watch the older ones every second of the day to make sure they are not discriminating against the baby and she is too small to be able to defend herself in any way. I would definitely bring this up with the girls' parents and warn them that any further discrimination from the girls will lead to immediate termination. If that goes well, then you can do as Cfred mentioned and try to do some work with all the kids on tolerance, acceptance, etc. But you will have to be very vigilant to make sure that there are not little remarks, etc being made towards or about new baby. This kind of thing is internalized and so damaging at this young age. Home daycare is like a family and so discrimination from the other kids will have more effect than that which comes from strangers or even classmates down the line.