TOPIC: Members and Discount Codes

I want to have three fee levels:
Non-Member: 65.00
Member: 45.00
Students: 30.00

Member and Non-Member are easily managed. I want to use a Discount Code for students, but if I make the discount code value $35.00 then any member who uses the student discount will be charged too little for the course.

Is there a way to do this without having multiple discount codes? I notice Group Registrations do not display an entry field for discount code. Can I have the Member's registration form eliminate this field as well? Or, is there a better way to accomplish what I am after.

Many thanks,
Ken