Originally Posted by
Often1
If one is really committed to this, the UK publishes an entire user "friendly" guide on what it needs to see in order to consider two separately-issued tickets as conjunction tickets and what the endorsements on each ticket must contain.
In this case, OP would need to have the endorsement added to both tickets by the marketing carrier (unless AA has the capability to do this for an IB ticket). This was last updated on 3/22/2018 and still refers to "ticket booklets".
https://www.gov.uk/guidance/air-pass...nected-flights
Nothing needs to be noted on the tickets if a "flight summary" showing both flights is prepared. (Whether both carriers must prepare such a summary now is something I don't know.)
From the link:
"The flights may meet all the other qualifying conditions for connected flights, but they’ll only qualify for the exemption if the connection is shown on the tickets
or a flight summary." (Emphasis added.)