Hair and Digestive Woes?

I have two Persians. They are both on Iams Hairball at the request of my female cat's breeder. My large Himalayan gets frequent hair, every other day it seems I am picking them up. The little female seems to be throwing up after her meal about every other week. I'm guessing the Iams Hairball isn't doing it for their digestive systems. What are some better cat foods they could be on to help with their digestive issues? The Himi is 14 years old, 11 lbs, the female is 8 years old, 5 lbs.