1.Place the water in large saucepan with whole chicken, tomato, celery, onion, parsley stalks and peppercorns; bring to the boil. Reduce heat; simmer, covered, 2 hours.
2.Remove chicken from pan. Strain broth through muslin-lined sieve or colander into large heatproof bowl; discard vegetable solids. Allow broth to cool, cover; refrigerate overnight. When chicken is cool enough to handle, remove and discard skin and bones. Shred meat coarsely; cover, refrigerate overnight.
3.Combine minced chicken, breadcrumbs, finely chopped parsley, cheese and egg in medium bowl; roll heaped teaspoons of mixture into balls. Heat oil in medium saucepan; cook meatballs, in batches, until browned.
4.Skim and discard fat from surface of broth. Return broth to large saucepan; bring to the boil. Reduce heat; simmer, uncovered, 20 minutes. Add meatballs and pasta; simmer, uncovered, about 10 minutes or until meatballs are cooked through and pasta is just tender. Add 2 cups of the reserved chicken (keep remaining chicken for another use), juice and coarsely chopped parsley to pan; stir soup over medium heat until hot.