I'm creating an event that has a surcharge for registering at the door. I'm thinking of using CiviDiscount to create an automatic discount on the registration price set, then expiring the discount after normal online registration expires. However, I also have another automatic discount for a membership type. Can I combine the discounts this way? Will I be better served by creating an admin only option for registering attendees at the door instead of having only one price set that has the discounts applied to it?