From what my understanding is:
If you are going during dates that do not have Open Enrollment, you can set up a class yourself. You need at least 10 students to sign up. There are many classes to choose from and you can find additional students by posting on the YES thread that was given earlier in this thread. If you arrange a class, you may buy discounted tickets for your student/s as well as additional tickets for the remaining part of your group that is not participating equal to the number of students that you have. If that makes sense to you. So if you only have child participating, you are eligible to buy one more discounted ticket for mom/dad/whomever.
If you are going during Open Enrollment, you may buy discounted tickets for your whole group, you are not limited to the one for one thing.