Wondering if there's a contribution or good way to have one order check another order to look if a product has already been purchased.
I'm working on making a store to sell classes, and they want the ability for family members attending the same class to get a discount, but that they can know who the members are. I'll likely do that by attaching the actual attendees to the address section, since they don't need to use addresses for shipping, but before I can do that, I need to have the order total check for other orders that have the same product purchased. Does such a contribution already exist? I scanned through pages but didn't see anything that looked especially promising...
I know I can do a quantity discount for the same order, and there's the Multiple Shipping Addresses (http://addons.oscommerce.com/info/2548) add-on that might work for splitting the order into parts, but if there's a better way to do it that'll cause less trauma to my source files, that would be good. It's already running over 30 contributions and trying to piece more in is always interesting. I'll do as many as are needed to get the store fully functional, but it would be good to do this in a way that actually works after it's done.
Thanks.