Originally Posted by
FlyerBeek
If you're making a change to your reservation (whether it's a paid change well beforehand or a CFC) you will only retain your original upgrade request timestamp on flights that remain unchanged in your itinerary. If you're changing flights (as this thread suggests) to an entirely different flight number - perhaps to get on a non-stop - then you will not retain your original upgrade request timestamp since, in effect, you are submitting a new upgrade request for your new flight. This has been my recent experience.
I am not sure on what facts how you're basing this conclusion, but it's incorrect.
If you're on the same PNR and you had made an upgrade request on the original flight, then the original time stamping is applied to the new (replacement) flight. I can see the timestamps in Sabre. If this weren't the case then there would be problems every time AA makes a schedule change that involves a change of flight number.
Note: the above apply only to X and R upgrades. Waitlisting in A or C (for SWUs) is different, and for these the time is indeed the one when you're waitlisted for each flight, and does not carry over across from prior flights.