AA Upgrades on DONE tickets
 

I just learned from this thread that DONE tickets issued by airlines other than AA are not eligible for AAdvantage mileage upgrades. I've been planning an ex-IST DONE (issued by BA) and this is a real disappointment.

I think I need to learn a bit more about reissues and how they work, but I am gathering that once a ticket is reissued every remaining segment on that trip is now "printed" on the issuing airlines stock. Does that mean that if let's say I was flying IST-LHR-xxx-LHR-LAX-... and wanted to upgrade LHR-LAX, that I would need to reissue the ticket after completing IST-LHR, and I would only be able to request the upgrades at this point as well? Seems kind of a waste of a reissue to do it so early...

This is new to me either. I have upgraded in the past on AA segments issued by other airlines. Rules must have changed.

This essentially means that you'll need to get tickets reissued. If you are planning to do this anyway, make sure that the initial ticket is setup properly (no special waivers or complicated calculations). Reissue is not a problem if you're simply keeping the itinerary and just changing airlines.