Thanks for the UA upgrade info above, which was exactly right.
Has anyone dealt with this scenario before:
UA ticket for a US-operated flight, bought through a cheap Internet travel agent. The travel agent's webpage allowed only a UA MP number to be put in the reservation; I wanted to put in my US Dividend Miles number. UA reservations says to call US; US reservations says to call UA. Who do I call to put my US number in the reservation?
Thanks.