In a large bowl, combine first 8 ingredients. Crumble beef and sausage over mixture and mix well. Form into 6 patties. Grill, covered, over medium heat for 5 to 7 minutes on each side, or until no longer pink. Top with cheese. Grill until cheese is melted. Grill buns, cut-side down, for one to 2 minutes, or until toasted.