TOPIC: Administator Override Fees

Can an administrator register individuals for an event, completing all fields and override the fees on the last screen? Basically making it a one-time complimentary sale. I want to select meals, t-shirts, etc. for this person, yet not have them being charged. These would be employees and volunteers that need to be registered at no cost.

Yes, this can be done two ways:

1) Frontend - you can create a 100% discount code and provide it to your administrators, staff, etc. Then they'd use the code to bypass payment.

2) Backend - admins can register users manually in the backend. No code is needed, but no payments are processed in the backend.

Thanks!

SIMILAR BUT CONSEQUENTIAL PROBLEM
I have created a 100% discount code for course instructor to use to register phone-in course applicants for courses that cost money. This controls maximum numbers, and lets the instructor register the applicant without having to personally pay the course fee.
However, a back end administrator needs to change the registration via DT Register/Records to delete the discount code (or substitute a zero percent code), change paid status to No, Payment Method to 'At the door' and enter the amount due.
All works except the discount code field. Even if it is cleared or changed, when saved, it reverts to the original 100% discount code. How can I edit the field.
Please help
Thanks