You shouldn't just stick new chins in with current ones. It's a good idea to quarantine all new animals for a month before letting them near your current ones. Both to let them settle in and to watch for illness. Ignoring the suggested quarantine period intros should be done over several weeks anyway. The cages should be set next to each other for awhile and then free time in a small chin proof room or pen. The bathroom works well for intros if you close the toilet, pick up anything they could chew on, and make sure the bathtub isn't too wet. Chins shouldn't get wet. After they are no longer getting excited or upset in free time then you put them together while you have time to observe them. I've rolled cages in to the hallway so I could watch them from the computer. Throwing them together is a bomb waiting to go off. They may be fine or as the other settles in it may start refusing to be submissive to the old one. In an instant they can go from friends to someone torn up and needing vet care.
