About 12 years ago my parents had a scheduled 3-week trip to Italy and France. It turned out my dad had some work stuff come up and couldn't go. We have the same name (not middle initial, but don't use them). I travelled in his place (He got the miles)

Same idea, but with hotels: - more than once I've had points show up in my accounts when my parents stayed somewhere and didn't confirm the correct frequent guest number.