So a couple days ago we tried introducing the tiny babies (almost 5wks) to the big boys (almost 12wks). I was nervous and worried they were still to small but they had to be separated from their "sisters" soon. So carefully they met, the big boys were very interested in cleaning the babies' butts, but otherwise seemed unbothered. So cleaned the cage, stuck them all back in, and continued meh. The babies stuck to a little bird house thing at the top mostly, occasionally venturing down or playing. The boys did their normal thing, wrestling and pile sleeping. I was still a little worried as the babies didn't seem to be interested in sleeping with the big boys. In fact they didn't seem to interact very much. Then just now I walked past and... Pile o' rats, including two tiny squished in the middle! Super excited! (Grey, Oolong and GusGus the fatbutts, Beelzebub the tiny on in the back, and Baniwi the light tiny in the middle.