I have two BT's. Jack is 26lbs and Emma's 15lbs. I also have a "mutt" named BB. She's a husky, pit bull, collie mix. She's 4 and weighs 80lbs and gets along well with them. My mom's dog is also mixed, we don't know what breeds because her mom was a stray, named Sandy and she's 6 and weighs 40lbs and she also gets along with them.
BB and Sandy only play when in their the mood, but they are more of a lay around the house dog. My uncle has a Jack Russell and they get along with him too. Except when he tries to get a little too friendly with Emma and she has to tell him to back off. (neither is neutered nor fixed)