Cook onions and celery in sauce pan with small amount of water until tender. Crumble cornbread and biscuits in large mixing bowl. Combine soup and one can of broth in sauce pan. Heat until smooth. Add the margarine and stir. Add cooked celery and onion including any cooking water. Pour over bread crumbs. Add pepper and sage. Toss lightly. Add additional chicken broth, as much ad needed to make a fairly moist dressing. Put in large baking dish and bake at 375 degrees until brown.