Combine the beef, chicken, fatback, soup bones, and ham bone, if using, in a large stockpot. Add 12 cups of water, or enough to cover the meats by 3 inches. Bring to a boil over high heat and boil for 10 minutes. Skim any foam from the surface as it rises. Turn the heat down to medium.
Drain the chickpeas and wrap them in a cheesecloth pouch tied with kitchen string (to make it easier to retrieve them for serving later). Add the chickpea pouch to the stockpot holding the meats.
Cover the pot, decrease the heat to medium low, and simmer for about 1 ½ hours. Skim the foam from the surface every 30 minutes; add more water if necessary to keep the ingredients covered at all times.
Add the sausages and 2 tablespoons of salt, decrease the heat to low, and simmer for 30 minutes longer, or until the sausages are fork tender. At that point, the chickpeas and the meats will be fork tender. When the meats and chickpeas are ready, retrieve the cheesecloth pouch of chickpeas and place in an ovenproof bowl; cover with foil and hold in a warm oven. Lift out the beef, chicken, fatback, soup bones, ham bone, if using, and sausages; place in a medium casserole or baking pan, cover with foil, and hold in a warm oven. Pour the broth through a fine-mesh sieve placed over a clean medium saucepan.
Bring 2 quarts of water and 2 teaspoons of salt to a boil over high heat in a separate large stockpot or saucepan. Do this about 15 minutes before the meat and beans are done. Add the carrots, potatoes, and cabbage, decrease the heat to medium, and cook for 30 minutes, or until the carrots and potatoes are fork tender. When the vegetables are ready, drain them into a sieve or colander. Place the carrots and potatoes on a large warmed platter (which will also hold the cabbage and chickpeas), cover with foil, and hold in a warm oven. Transfer the cabbage to a colander and press thoroughly to eliminate any excess liquid.
Heat the oil over medium heat in a large sauté pan. Add the garlic and sauté for 2 to 3 minutes, or until golden. Add the cabbage with 2 teaspoons of salt and the pepper, and turn several times in the oil and garlic to heat through and blend the flavors, about 5 minutes. Transfer the cabbage to the platter holding the carrots and potatoes, and keep warm.
Heat the tomato sauce in a small saucepan over medium heat until hot, about 5 minutes. Remove from the heat, cover to keep warm, and leave in the saucepan until ready to serve.
Bring the broth to a boil over high heat and add the pasta, if using. Boil for 3 to 5 minutes, or until the pasta is almost tender. Remove from the heat and keep warm.
Cut all the meats and sausages into 1- to 1 ½ inch pieces and arrange on a warmed serving platter. If the soup bones contain marrow, remove the marrow, spread it on the toasted bread, sprinkle it with salt, and keep warm; otherwise, discard the bones. If you have used the ham bone, cut the meat from the bone and add it to the platter.
Remove the chickpeas from the cheesecloth pouch and add them to the vegetable platter.
Serve ¾ cup of the broth with pasta in a small or medium bowl as the first course, reheating it if it has cooled. Serve ½ to ¾ cup of the chickpeas, 2/3 cup of cabbage, ½ potato, and ½ carrot with 1/3 cup of the tomato sauce. (This can also be served on the side, if preferred.) Serve ¾ of 1 cup of the meats and sausages, along with the marrow-topped toast, if using marrow bones, as the third course. Alternatively, serve this meal family style. Provide plates and bowls and allow the guests to serve themselves. The broth is delicious as is with the pasta and it also nicely complements the meats and vegetables.