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Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
Have tried to call and ask? In fact, if you book by phone, you might be able to specify the ticket stock you want if it's reasonable.
Is this corporate travel, one of their city travel agencies, or PTS/CTS?
AFAIK AmEx doesn't do funny stuff with plane tickets so if it's all UA segments, I would certainly expect UA ticket stock. Otherwise IME they follow the rule of ticketing on the stock of the carrier operating or marketing the first longhaul segment.