If I expect, based on past experience, that they won't be eligible for anything, I don't give them any crucial parts. They're always doubling something else, or playing a 3rd part that's expendable if they fail. If I had more than one band I would make sure they were in the second band. For marching band I have some dots that are expendable. It's usually an arc across the back of the main forms. I assign those dots to kids who haven't "gotten it," musically or visually, or kids who are probably going to fail their classes. Those kids only march at games. IF they're eligible for contest, they can help on the prop crew.