Discard hikashop's username and add a student's username

Hi,
I'm using hikashop and SSO. Then, when the custom purchases a course, the username of hikashop form registration becames the student's username in moodle.
But if the person who buys the course is not the student, how can I add a new username for the student?

Moreover, In the mapping data section, I can not add a new username for the student

How can I solve it?

Thanks in advance!
Leonora.

What you want is not possible at the moment: when a user buys a course, he buys it for himself.

Only different way is "buy courses for children" where a parent user can buy courses, and then assign them to their children.