I would ditch the supermarket stuff and just go with a professional brand. Eventually your cat will have to fold and just eat it. you can start by mixing half and half with whiskettes or whatever, then gradually reduce it until its only the vet stuff. chuck in ghe occasional raw chicken wing for dental health. The problem with fussiness is that it could over time limit the range of nutrients your puss is getting. When I was feeding my cat fresh food I gave her lots of variety (yes this included some veg too) but I don't have a lot of faith that the supermarket brands contain quality nutrition. Our Puss is on a vet dry food, has been now for several years. She's kicking on towards 20 years old so we must be ding something right.