Quickly update classes with substitute teachers

I'd love to be able to do a quick update if we have a substitute coming in to teach a class since we're drop-in only. For example, I'd love to have an admin feature where I take the following steps to update a class teacher:
1. Select Class

2. Instructors

3. Substitute field added here

I'd love for this to automatically update our schedule to show there is a sub & I'd love for the sub to automatically override the payroll for that class.