I used to give Nefertiti sensitive stomach food, which did work for her.
When Sluggo wanted just Sheba, and was literally not eating other foods, I thought that it was a preference. And, it might be to a degree.
However, we got her to eat the food that the other cats also eat the other day, and she threw it up...so maybe other foods are just not agreeing with her. She is now heading towards 20, so perhaps that has had something to do with it the past year. Before the past year or 2, she'd eat pretty much anything.
I'm glad that Baby and Beau can eat other foods, and hope that it remains that way also. My other cats, even the older ones, do fine on other foods that I buy.
Love All Life, Thank You For Posting! :)