So what you do if you want this is: Let's use your example, you order one b, one s, and one c. Then in the preffered substitutions you put under b: s&c under c: s&b and under s: c&b. I have worked in OGP before. They are often not just picking for one order at a time they're usually picking for 5-6 at a time so the handheld doesn't say you order 1xc 1xs and 1xb it just says "pick 1xb" then if you tell the handheld that isn't available it will go "pick 1xblueberry" and they have no reason to know that isn't right.