I have a mom rat that has seven little ones, just over three weeks old. Today someone brought me two baby rats for her to foster, between three and four weeks old, and she keeps attacking them. I figured that she would be great with them, consitering their the same age and about the same size, if not a little smaller then her babies.

I cleaned the cage, and had the two new ones in with her babies in with hers to make their sents mix, but she keeps tracking down and singling out the new little ones.

How can I get this to stop? I have the little ones hiding in fear in a paper towel roll... Some advice, please?