The best thing I can think of is for you to take one of Brixton's blankets to the breeder, so the puppy can sleep with it and become familiar with his smell. At the same time, ask for something with the pups smell on it and expose Brixton to it in the same way. The purpose is to allow the dogs to become familiar with eachother. When you do bring the puppy home, the "aromatherapy" will bridge the gap and neither dog will think of the other as a stranger.
This could be the simplest, most proactive thing you could accomplish before picking up the puppy.