Hi George, thanks for the reply. The issue is that we don't want the courses to appear in Record of Learning. If we use audiences, the user is enrolled in the course and it will appear in their RoL. 

The Instructor does not have to complete that learning - they are just instructing - so the course should not appear in their RoL as assigned. 

I've continued to play with this. It appears that we can assign the Instructor role at the Category or Course level using Users > Other users and the user is not enrolled. But to assign the Instructor only at the session level (not course or category), the user is enrolled. 

Thank you!

Susan