
Thank you for your answer.
In the example you give: users can choose between three groups:
- Students
- Ex-students
- Teachers
With your configuration, In profile module you can select one of this three groups.
and only one of this 3 groups.
When a student becomes ex-student: he can go change his profile but the modification will not be done: he will stay in student group.
To make it, there is probably something to add in
modules/profile/edituser.php
@+
Z