Yes—there are online options, although replacing an existing number can be harder than adding one.

1. Try [BA’s Manage My Booking](https://www.britishairways.com/mmb) with your booking reference and surname. Look for the frequent flyer details, select **American Airlines / AAdvantage**, and enter your AA number if editing is available. BA officially supports adding partner frequent flyer numbers, but its FAQ doesn’t guarantee you can replace an existing one. [BA FAQ](https://www.britishairways.com/travel/mmbfaqs/public/en_gb)

2. If it’s locked, try retrieving the reservation through **Royal Jordanian’s Manage Booking** at [rj.com](https://www.rj.com/en/). Travellers report using other oneworld airlines’ websites to change the number on BA reservations; this workaround depends on the booking. [Traveller reports](https://www.reddit.com/r/BritishAirways/comments/194u6cz/)

3. If that fails, **BA web chat** is a phone-free fallback: a traveller with the same BA-to-AA problem reported getting it changed through chat in March 2026. [Report](https://www.reddit.com/r/BritishAirways/comments/1rj9iqz/change_frequent_flyer_info_in_booking/)

Ask for the AA number to be applied to **every flight segment**, and check the saved details afterward.