Prepare biscuits (enough to make 4 cups crumbled), and one 8x8 inch pan cornbread according to package directions. Cool and crumble. Preheat oven to 350 degrees F (175 degrees C). In a small pot, combine onion, celery, margarine and chicken broth. Bring to boil and cook vegetables until tender. In a 2-quart casserole dish, combine 4 cups crumbled cornbread, 4 cups biscuit crumbs, salt, pepper, sausage, chopped eggs and sage. Pour broth and vegetables over bread mixture, and stir until combined. Bake in the preheated oven for 30 to 45 minutes.