Hey Lynz! Absolutely, always happy to help.
While I did initially mean to enroll them as an observer, if you find that it would be beneficial for the supervisor of the student to be added to the course as a Teacher, TA, etc. and to have those permissions, then you are absolutely able to! This is ultimately your call, and you can do whatever you think is best for your situation. I'm just providing some general suggestions!
Teachers and TAs also have access to student grades as well, and can also edit them (if using a paid canvas account this can be controlled by a canvas admin, but usually it's always enabled for both teachers and TAs).
I hope that helps clear things up, let me know!
- Noah