You have to be careful when introducing chinchillas, one they should be kept separate for a 30 day quarantine period, A: to watch for disease and B: to monitor the new chins eating , drinking and bathroom habits and C: to give the chin a chance to acclimate to its new environment. Also, there is no guarantee that the chins will get along so you may end up with 2 cages and 2 playtimes so be prepared. As far as your question, many chins can be trained to go back to a carrier and transferred to a cage or you can catch them in a dust bath container and take them back. Many will just go back to their cage if the cage is in the play room.