I have 2 Main Coon kittens in good health and a 14 yr old Main Coon who has IBD and frankly is in terrible shape.The old guy was free fed most of his life so he's a nibbler and prefers dry but will hit canned.Issue: The kittens hoover up any food 24/7. They are eating machines, and my Old Guy needs to be able to eat some dry when canned isn't available but the dry kitten food isn't appropriated for IBD cats. Question: Would it be okay to change out the dry kitten (Pro Plan for kittens which is Chicken and Rice) with Royal Canin Hypoallergenic dry?Current diet for all cats: 1 can/day of Nature's Variety Grain Free (Chicken, Duck, Rabbit). Pro Plan Kitten (Free feed). I also have Royal Canin Hypoallergenic available but can't leave it out because the kittens finish it off.Should I quarantine the Sr. Main Coon?Should I try the Natures Variety Limited Ingredient dry?All suggestions welcome.