Welcome back! I am having food issues too right now. I only have 4 cats but in kind of the same boat as you. 2 are seniors, one is middle aged and 1 is 2. Feeding is a challenge for sure!! We've had issues with crystals in the males. The youngest is the only female.
I have discovered that the cheap foods, ie grocery store brands and Walmarts actrium cause tummy upsets following by much throwing up especially by one, who is going to t he vets this week. I think his thyroid is likely out of whack.
All are very, very fussy eaters! Right now I have them eating Orijen for kibble, they all like it. Right now for canned, we're trying Nature's Variety Instinct Rabbit, they have several different formulas and this is one I can get here. I used to have them on Natural Balance, tried some the other day and got overnight throw-ups. Wellness agrees pretty well and Merrick, although I find there's alot of stuff in Merrick that they don't need. So I'm trying to limit the ingredients I'm giving them.
Haven't tried making my own food. I don't really want to have them not eating and they won't touch raw. I don't know about making home cooked, for dog's it's pretty easy but cats seem to have more demanding dietary needs.
Good luck. If you do want to try making your own, Global over on Sir John A, if they're still there, I moved out west about 4 years ago, carried Urban Wolf and they also carry a formula for cats, called I think Urban King. I used the Urban Wolf for my dog and it contains all the good stuff for adding to your own meat. It can be cooked or raw. The place out in the township...oh on the road Walmart's on with the vet's office, also carried it. I think Bird's and Paws on Brock St does too. I'd try them for other stuff too, they sometime got stuff in that no one else did..