I am faced with getting my new Yorkie's sister. I don't know if this will be a good idea or bad. They both come from the same litter, but they play so well together and I don't want to seperate them but I don't know if having in the same home would mean that they both will be a little harder to train. I do know that they will love each other's company but won't they try to mate later on if the female is in heat? I don't want to spay or neuter them right away but I do want them to stay together....