I currently have two adult boxers (3 and 4 years old both neutered males). I had been thinking about adding a third dog to our mix and the breeder that both of my guys came from just happens to have a 3 year old spayed female that is looking for a new home. I am a little undecided since my two get along so well - does anyone have any advice on adding a third dog? Does it throw off the balance of the two and one is left out when playing? Thanks for any advice that three boxer owners can provide.