I have two yorkies - one almos 8#'s and one just 5#'s. They play well together. The bigger one (Katy) stands over the little one (Sophie) and tries to be dominant but only in a gentle way because the little one is very fiesty! The only problem I have is Katy is quite jealous and pushes herself between me and Sophie when I am paying attention to Sophie. I guess Katy thinks I am only hers. I am currently letting Sophie sleep with us now and Katy has been very good about this and actually snuggles with Sophie on the bed at night.