I have read the stickies and searched through the threads, and believe I know the answer to the following two questions, but I'd like to make sure. (I've also spoken with the AAdvantage desk and received quite a range of answers; hence my uncertainty.)

(1) If I want to upgrade particular segments of a DONE5 ticketed via AA, (a) can I only do this for the AA segments, and (b) if so, is it 25,000 AA miles per AA segment?

(2) Other than the obvious one of not using miles, is there any benefit to using an eVIP to upgrade rather than miles? My only two upgradable AA segments are NOT contiguous, to the extent that's relevant.

With regard to question 1(a), I know that I can't use AA miles to upgrade a BA or CX flight, but is it the case that I also can't use BA/CX miles to upgrade a BA/CX flights where those tickets are issued on AA ticket-stock?

With regard to question 1(b), one person at the AAdvantage desk told me that I only needed 15,000 miles to upgrade from D to A (but 25,000 to upgrade from L to D), but the Exec Plat desk said the correct number is 25,000 for upgrading from D to A. I had also thought the correct number was 25,000 miles, but now am uncertain.

Thanks very much, and I apologize that this is ground that's been trod before, but, as I said, the AA desk (and the BA desk as well) seems a bit unsure about it.

You can upgrade AA segments with miles/eVIPs quite happily. an eVIP/miles upgrade can upgrade up to 3 segments which do not have to be contiguous but do have to be in the same direction. Depending on the AA sectors you have, you may be able to use one award/eVIP for both sectors

I don't know about CX, but iirc, to upgrade on BA, a ticket has to be purchased from BA or from certain agents

The number of miles needed depends on what you are trying to upgrade; if it is something like North America to Europe/Asia, then 25,000 is correct . The AA website is pretty decent at detailing mileage requirements ( https://www.aa.com/aa/i18nForward.do...anAirlines.jsp )

One area where an eVIP can beat miles is on something like NRT-JFK-LHR which would require , iirc, 1 eVIP but would require 2 * 25k awards

Dave

Thanks very much Dave. Based on my conversations so far with AA, I guess I'm pessimistic that I'll be able to upgrade the BA (LHR-MRU) and CX (HKG-LHR) routes I'd be interested in upgrading. (Obviously I could always pay $3,600 more for my ticket to make it an AONE, but that's hard to justify when only four or five segments can be in A.) Thanks though...

In oneworld unfortunately you can only upgrade flight on the airline of your FFP. Star Alliance is better in this respect.
There are exceptions however (Asia Miles for BA).

Thank you, and I apologize if I'm misunderstanding what you're saying, but I (sadly) accept that I can't use my AA miles to upgrade my BA flights. The question though is whether I can use my BA miles to upgrade my BA flights that are part of my DONE ticket (which has been issued on AA ticket-stock). Thanks very much; sorry if that was unclear (or sorry if I misunderstood what you were saying above)...

Sorry, I didn't understand you correctly. Yes you can use BA miles to upgrade flights on BA.

That's what I had hoped someone would say. As a logistical matter, do I do that through the AA desk or the BA desk? Each one keeps pointing at the other and saying, "It's his problem" or "You can't do that." Thanks.

But only if the ticket has been purchased from BA.

From the BA board ultimate guide:

So does that mean we're back to what I had originally believed--that I can't upgrade the BA segments w/ BA miles on my AA-ticketed DONE5? Thanks.

My mistake, I didn't know BA also has this rule in the US. So unless AA is considered to be a BA preferred travel agent the OP will have to survive BA J.

The OP's will is strong, and he will try.

FYI, from a prior thread: http://flyertalk.com/forum/archive/i.../t-507382.html.

Correct. If you want to MFU a BA segment the ticket must be purchased from BA either on the website or over the phone, or if purchased in the US, from a BA preferred travel agent. So, to rephrase, if you purchase the ticket from anywhere but the US the ticket must be purchased from the BA website (impossible for rtw tickets) or over the phone from BA (purchasing from a travel agent in EUR or Africa will not allow you to MFU). The ticket will, of course, be issued on BA ticket stock. I doubt that your questions to AA about MFUing a BA segment will result in any consistent answers because the AA people will necessarily be guessing or trying to apply their own logic. You should direct questions about MFUing to BAEC.

Thanks very much for this.

Good luck with it. I would give BAEC a call, maybe you'll get lucky, but don't don't get your hopes up too high in case you don't (which, imo, is more likely).

Is there actually any award availability for LHR-MRU? This is a very hard route to get award availability on.