Since British Airways, Iberia and Aer Lingus all share the same Avios program, you can use your Travel Together Ticket on any of these airlines. You can also redeem this companion ticket on their subsidiaries and franchise partner airlines, including CityFlyer, EuroFlyer, Iberia Express, Air Nostrum, Aer Lingus U.K. and Emerald Airlines. On all of these bookings, your trip doesn't have to originate in the United States.