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.