If you hit a drive and everybody in the group sees where the ball went and the location. But on your way up to the ball you see another group going the opposite way hit a ball near where you think the ball landed. After searching for the ball you find another ball that is not yours but was near where your ball should be. What is the ruling for somebody else in another group hitting your ball? Do you have to go back to the tee and rehit your tee shot and take a stroke penalty for lost ball? Take a stroke penalty at the spot where the ball should be and continue on? Or get a drop there with no penalty?