... with other chins.
Take it slow! First off, make sure they are the same sex. Very important! Let the new one get used to their new home before doing anything. Also, make sure the newbie is healthy. It's highly recommended that you quarantine any new chins for 30 days before introducing them to your current herd, in case they are carrying an illness that can't be seen yet. A vet visit would be great, be sure to ask them to check for intestinal parasites as well.
When the new one is settled and had a health check, put them in a cage beside your other cages. Let them get used to each other's smells. You can swap cages as well. Do not put them in each other's cages together. It's just too dangerous at first... do neutral play areas/times. Somewhere neither has been before. There will be humping and chasing, its normal. Break it up if it gets to be too much. Start off with short sessions, 5-10 minutes. When it starts going well, you can have play time in the normal play area. When that goes well, you can clean out the cage that you want them in really well, then let them explore the cage together. We wouldn't house them together until they've taken a nap and eaten together! It can be highly rewarding but will take patience!
... with you!
Again, take it slow! Some ideas that can help are just talking to them, or reading. Sit by the cage with your hand inside and let them come to you and smell and explore. Sit in their play area and let them use you as a jungle gym. Try sleeping with a piece of anti-pill fleece for a few nights to get your scent on it, then put it in their cage so they can sleep with your scent. Hand feed them pellets. Again, it can be highly rewarding but will take patience!
Mushu & Gizmo, owned by Elizabeth Lee Ateeq
Kira, Joey & Chloe,
owned by Tina Sauer Harshbarger