It would be very neat if you could, from a single screen add teachers/students to multiple courses.

Two ways that this might be done:

With something like Meta-Courses, but upside-down so that anyone assigned to teach/enrolled on course A also gets added to course B, C, D.

A page similar to assigning students to a single class, where you get a big list of enrolled and unenrolled students and move individuals between the two lists with arrow buttons. Obviously in this case you would have a single individual and lists of courses they are enrolled/teach on or not and you can (un)enroll or (un)assign them as teachers by clicking arrow buttons and moving them between the lists.