We have an item say a girth, you can buy black or brown, then select a size. But to buy this item you have to add a liner to it which could be neoprene, fleece or leather. You can't technically buy the girth without a liner but some people will want to change and swap liners. So currently they can select the girth e.g 48" Cinch in brown. I want them to not be able to add to cart unless they have picked 48" cinch in brown with a 48" leather or fleece liner.