Cook 8 ounces elbow macaroni as the label directs; drain and rinse under cold water. Whisk 1/3 cup each mayonnaise, sour cream and barbecue sauce, 2 tablespoons relish, 1 tablespoon yellow mustard and 1 teaspoon sugar in a large bowl. Add the macaroni, 2 cups cubed barbecue-flavored rotisserie chicken, 1 diced red bell pepper, 3 chopped celery stalks, 1/2 diced red onion and 1/4 cup chopped parsley. Season with salt and pepper and toss. Refrigerate at least 1 hour.