When creating a schedule with multiple (at least 2) student per slots (Maximum number of students per slot set to 2 for example).

2 appointments are created. You can register 2 different students.

If you want to revoke or change one or many of those student it's impossible, even through the slot edit page as a teacher or admin.

When you save the page reload but your changes are not taken into account.

You must revoke them all from the slot, and enter the others again.