I am looking at some award flights in April 2025 in J: JFK-LHR-AUH. JFK-LHR operated by AA, LHR-AUH operated by EY. At 70K, this seems like it should be a J partner award all the way through. But the LHR-AUH leg is in economy, my guess because EY only seems to release J or F award space to AA close to travel date.
If I book this now, and J space for LHR-AUH becomes available through the AA site close-in, will AA be able to upgrade just that leg since technically I already paid the miles for it?