So, by adding your Known Traveler Number to the American Airlines app, you'll ensure it's applied every time you buy a ticket from American Airlines.

How to buy tickets for Dallas Stars’ Western Conference finals battle with Edmonton Oilers The Stars will host Games 1 and 2 at American Airlines Center, along with Games 5 and 7 (if needed).

I contacted American Airlines, which agreed to refund the second set of tickets. But it has only refunded one of them. I disputed the charge for the second ticket through Citi, my credit card.