Independent Contractor Questions

Two questions...I am an independent contractor as a referee for high school sports.  There are three of us that work a game...and the school just picks someone to pay the mileage to.  I don't like this plan, but that's what they do.  Sometimes, they pay mileage to referee #1 and referee #1 drives.  Sometimes, they pay mileage to referee#1, but referee #2 drives.

In case #2, let's say that I'm referee #1, and I did NOT drive...but I get paid mileage.  I get a 1099-MISC at the end of the year, and it includes all mileage paid throughout the year...and is then taxable.  How do I handle being paid mileage money when i didn't drive? 

Also, for when I am paid mileage...and I DO drive...our group's policy is that I give the "riders" some of the mileage money for "windshield time".  How do I deduct this payment to others that are in my car?

Thanks!