Is there a way to add a selection to make purchasing additional items manditory during the registration process? We use the additional items to track sign-ups for different sessions, and limit the types of businesses or industry and designations of attendees such as existing business owners, start-up businesses. We as of yet have not charged for the items, but it is crutial to our tracking and having the right type of diverse crowd for our sessions. So the way we use the Additional Items is not so much for a tangible product, but more to sign up for an individual break-out session.