A studio can opt to generate a Group Activation Code for customers to enroll themselves into a group. The field to input this code can be found in the My Info section of their account. Once put in the group, the field disappears, meaning that a customer cannot enroll themselves into a second group. The staff would have to manually put the customer into other groups. If removed from all groups, the customer will see the field again and can put themselves in whichever group they have a code for again.

To include the option for Group Enrollment upon sign-up: Configure Customer Fields