I know this is over, but for future reference, if some one is allergic to something-they know it and that will be the first thing they tell you-if you can't accomodate that, they go somewhere else. Suffereing from a severe nut allergy myself, I know. I also know that any time I had a party, people have called me to say John Doe is allergic to so and so, and asked if I was going to have it at the party. Allergic people know. That's why I would also recommend never giving ingredients to anyone-especially after the fact. It's makes it too easy to pick something out and give them ammunition.

Maybe think about getting a stamp made-or typing a statement on contracts-something to the effect of John Doe has no allergies, has agreed on specific cake & frosting flavors therefore company x can not be held responsible for any allergic reaction liabilities. At that time, if you have no objections, you could list your ingredients so they can review and sign off on everything.

I know I'm most likely going a little overboard, but a few bad apples spoil the whole bunch and you need to protect yourself. People will do or say anything to get out of payments or look for reasons to hold others liable.