For vegetable soup, combine soup bones, 12 cups water, whole onion and bay leaf in a soup pot. Bring to boil and skim off foam. Reduce heat and simmer, covered, 3 hours or until meat falls off bones.
Remove bones, onion and bay leaf. Remove meat from bones and dice. Skim fat from stock. Add meat, chopped onion, potatoes, carrots, tomatoes, cabbage, celery, beans and parsley to the pot and season to taste with salt and pepper. Bring to boil, then reduce heat and simmer, covered, 1 hour or until barley is done and vegetables are tender.
For dumplings, combine flour, baking powder and salt in a medium bowl. Add milk and stir until moistened, then drop by teaspoons into the vegetable soup. Cover and cook 10 minutes or until heated through.