Provide a way to limit the number of child courses/sessions that a user can enroll themselves into.

Provide a way to limit the number of child courses/sessions that a user can enroll themselves into.

Provide a way to limit the number of child courses/sessions that a user can enroll themselves into.  When setting up a parent with many different children sessions at different dates, times, and locations, we should have the ability to limit enrollment to one session per user.