It will really depend on how they play together and their personalities. This is a for sure meet each other before you decide what to do. I have an almost 3 lb boy and he is just fine with everyone and mostly plays with our 5 1/2 lb male. My stepmoms dog is 15ish? (not a yorkie) and VERY hyper. We have to be very careful when they are around each other. My friend has a 12 lb shihtzu and they all get along great with her
