Preheat oven to 400°. In a large bowl, whisk egg, milk, minced onion, 2 tablespoons chili powder, salt and pepper; stir in crushed crackers. Add beef, sausage and cheese; mix lightly but thoroughly.
Shape mixture into 1-in. balls. Place meatballs on greased racks in 15x10x1-in. baking pans. Bake 15-18 minutes or until browned.
Meanwhile, in a 5- or 6-qt. slow cooker, combine soup, water, brown sugar and remaining chili powder. Gently stir in meatballs. Cook, covered, on low 4-5 hours or until meatballs are cooked through.