Hi, a girl who I work with booked a holiday with a group of her friends but could not go due to illness. She called her insurance company who have sent her forms to try to claim for the money back from her holiday. Her insurance company have told her that she is likely to get the money back if she can produce both a doctors note and also a note from the airline confirming she did not fly. So it may be worth speaking to the insurance company, however, I don't think someone else will be able to claim on behalf of your friend.