If you have to add a course after you have already registered, you will usually need to fill out a special form.
Depending on the timing of the request, the form may require the signature of the instructor whose course you are adding.

Question

Quizplus · Accepted Answer

Most educational institutions have a process for adding courses after initial registration, often requiring a form that may need the instructor's signature, especially if the request is made after classes have started.

If You Have to Add a Course After You Have