Fussy eaters / Supplements?

[Puzzles]

I'm after some advice if possible please ... the 3 kits are becoming very fussy eaters ... they much prefer Tigger's food to theirs They refuse point blank to eat Bozita, Alamo Daily Menu etc & are even going off Schesir Tuna now (they've loved it since they arrived here), they also flatly refuse to eat anything that contains chicken. They seem to prefer Tigger's Sheba, Felix, Friskies and the Purina wet foods. They still have a variety of good biscuits, but I try and make sure that they have a good mix of wet and dry. It's a nitemare, I'm chucking away soo much food at the moment. Does anybody have any other ideas please? And do you think it's a good idea to give some kind of supplement?