I'm going out to the Salt Lick (an awesome bar-b-q joint that doesn't serve alcohol, but allows you to bring your own, I believe) with some friends and their parents to celebrate someone's graduation. My 20-year-old friend and his parents want to drink with the idea that I'll drive them home. I plan on carrying and not consuming any alcohol.
My questions:
1. Can he drink legally in public with his parents within arm's reach? I think this is true, but I wanted to make sure I understand it correctly.
2. Can I get in trouble for buying alcohol with him in the car (with or without his parents present)?
I think I know the answer to the second question (ok with parents present, not ok with just him there), but I'm curious. How would a LEO know the difference between me buying alcohol for him to legally drink with his parents as opposed to me getting arrested for providing alcohol to a minor?

Just trying to stay legal while everyone has a good time.
