I'm going to take a trip to London next year with a cousin. I've got 60,000 United points to pay one way for both of us. However, she's got over 30,000 US Airways points and I've got over 30,000 American points. We'd like to fly together on the leg home, too, but not sure which way to go. Should I use my American points, fly American, and let her use her US Airways points to fly American? Or should I use my American points to fly US AIrways with her? I know you can buy one way trips on American but not sure if you have to pay roundtrip on US Airways for a one way trip. Thanks!