My daughter is ticketed on BA from LAX - Heathrow - Madrid - Seville. She is visiting her brother who is living in Seville. They have decided that they would like to spend a few days in Madrid, then travel by train to Seville. I'm not sure how she can "cancel" the Madrid to Seville portion of her trip. Will she need go through Customs in Madrid? If so would she be able to get her luggage and meet up with her brother rather than get on the Madrid - Seville flight? Please let me know the best way to do this. She is flying out on Christmas eve.