I suggest that your relative keep her bags unlocked, that way it would make any customs inspections easier.

If she fails to retrieve her bag and manages to exit customs, you can then go with her to the AA lost baggage desk and file a claim.

Since the bag is coming from an international destination, be prepared for AA to ask you to fill out a special customs form listing all the contents of the bag and authorizing customs to inspect the bags without your relative present.

If you are lucky, the bag may even then get forwarded by AA to the final destination (after it has cleared customs).