I booked two round trip tickets from Charlotte, NC (leaving *****) to Detroit, MI (DTW...

I booked two round trip tickets from Charlotte, NC (leaving *****) to Detroit, MI (DTW) returning *****. The Record Locator was FUVSOU. Unfortunately, my traveling partner fainted upon getting out of the car on the way to the flight. To make a long story short she had to be taken to hospital by ambulance. I cancelled our flight. The trip was to visit my son and her daughter who recently moved to MI. I then had a credit with AA for both tickets. My daughter-in-law flew to Charlotte because of her mom's condition. She is flying back to Detroit Saturday. I wanted to fly back with her (to see my son), so I booked on the same flight (**** on *****, returning ******, Record Locator LUUCGZ). I paid for it because I was told that I would have to call a reservation agent to use my AA credit. I could not do it online and it was impossible to get through on ***** due to the weather at various airports. There were only a few seats left on that flight and I wanted to get on it. So, my question is: can I apply the credit for one of the cancelled ***** tickets (mine) to the one I just purchased ? Both tickets were purchased using my AAdvantage Mastercard (****************). My AA Advantage ID is *T*WP**.