Layer potatoes, carrots, 1/2 of the onion slices and beef in slow cooker.
Mix Gravy Mixes, flour, Italian seasoning and celery salt in small bowl. Sprinkle all over beef. Top beef with remaining onion slices. Mix water and wine; pour over top. Cover.
Cook 8 hours on LOW or until beef and vegetables are tender. Add parsley flakes; stir well. Remove beef and vegetables to serving platter. Spoon some sauce over beef and vegetables. Serve remaining sauce on side, if desired. Thicken sauce if desired.