At least down here the issuing carrier doesn't have to be the first international sector operator (or whatever). As Al B says often AN would issue RTW tickets for other carriers. Indeed I recall one or two I got ticketd via AN that had ZERO AN sectors on them!
Recent RTW tickets have been on 618 (SQ) ticket stock (first int. flight on OS) and UA 016 stock (SQ operating first flight out).
I understand not wanting to have a RTW ticketed on 016 stock in case UA fails. Perhaps one should also avoid AC stock too, given that they are in ch. 11. also.
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RichardMEL, UA 1K
A Star Alliance Member.