I have the same problem, Joey needed the special I/D food and Bob needs a weight reduction R/D food. Both Hill's

I had it worked out for a while. I would use diet food as dry and that way they could free feed. Then I feed Joey her own wet food at night and I also kept some diet wet just in case Bob wanted some. I think that Bob is a little off, he doesn't really like wet food. However, every once in a while he will want some because Joey is getting it.

Now that all changed when Joey started to get sick last Thanksgiving. So I made the decision to put out dry I/D and let Bob gain a little weight for a short time. I thought that it was better to get Joey under control first.

I think that I am going to move there dry food to Royal Canin and mix there sensitive stomach and diet together. Then if we can get Joey all better and she no longer need to eat sensitive food go to the Royal Canon weight reduction and the wellness wet food for Joey. Then keep a couple of cans of the Hill's R/D for Bob.

So basically the same thing as before with different brands of food.

I will hopefully be able to do that again in a couple of months. For me it is all a matter of compromises between the 2 kitties needs.