A codeshare flight is a commercial flight that is operated by one airline, but marketed by others.This concept can be confusing for passengers, but ultimately it can be a valuable service.The result was that each airline could service more areas, without technically expanding its service.Multiple airlines began to follow suit, and it is not unusual to see three or four airlines all selling tickets on the same flight.Product that supports automated pricing of a wide range of services from traditional in-flight amenities such as meals and entertainment to a variety of pre- and post-flight options including the sale of merchandise.
However, once the ticket falls under "airport control", which it does 24 hours before departure, then the operating carrier has some ability to modify the ticket, but it is difficult and many of the staff at BA are not trained to use AA's system.
This might limit the degree to which you can travel with your refund credit.
Show your membership card from: Any grocery store like Stop & Shop, Big Y, Price Shopper and others.
You also may not know who your validating carrier is if you book through an online travel company, or with a travel agent.
You can ask, however, which can help you make up your mind regarding which agent or service to use.