Getting two chinchillas together takes time, lots of it. And, since there is such a size difference between your two you need to wait a long while. I always prefer that chinchillas be about the same size before a real introduction. Otherwise, if there is a fight, the little one would be seriously hurt or killed. Just keep letting them get to know each other in side by side cages for awhile. Its enough that your new chinchilla is trying to get used to you and a new house. He can worry about a new cage mate later.
