I just booked two tickets for my parents online through the United website. They will be traveling by bus from Munich to Salzburg on British Airways "flight" number 9300. I paid for the tickets with my credit card. Upon booking, the itinerary summary says, "International travelers, please. . . Bring the CREDIT CARD used for purchase." Now, I won't be with them on this trip. Is it going to cause them problems at check-in if they don't have my credit card? What is the best way to handle this? Thanks for your advice.