[margaritaville]

I think I would switch her to the Natural Balance. It will make your life easier to have them both on the same food.

When you switch her, do it slowly. Go a couple of days with 3/4 Purina and 1/4 Natural Balance. After seeing how she tolerates this move to 1/2 and 1/2 then to 1/4 Purina and 3/4 Natural Balance, then to a total switch. By switching slowly you get to see how they are adjusting to the new food and avoiding digestive upset.