An organization has an "invite only" event. They have given out discount codes to those who are invited to the event. They want to limit the registration through the discount codes, only allowing those who have a code to register on the Registration form through Blackbaud Sphere.
This is currently not a feature within the program.
Blackbaud has an Idea Bank our clients can go to and enter any suggestions they have for our programs. You can go to http://sphere.uservoice.com/forums/143074-sphere-product-whiteboard/ to enter suggestions and vote for you favorite suggestions as well. This is a direct line to our programming team and they look at this to determine future enhancements to the software.