We have a day camp and we want our returning campers to be able to register a week before any new campers. It would be nice if sportsman had an option to require that a person has already been in one or more activities XY or Z before allowing them to register for a new specific activity. This would also be helpful for skills-based athletics like gymnastics, in which students progress in skill level over several sessions (beginner is required before intermediate which is required before advanced, etc). Having a code that we could email people who we deem eligible would work fine, but a checkbox with a drop-down that shows past activities could work too, maybe even better.