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...