hi flyertalkers!
a little background on the reason i asked my original question. this summer i'm planning a trip from moscow and return from helsinki. i need 80k to go in bf and return in y and i'm a few miles short now. the plan was to buy the united seat to moscow with ua miles since it's on their metal and then a 1 way home from helsinki on co metal with co miles.

plan b is to buy the r/t in y with co miles and when i scrape some more co miles together upgrade the moscow leg. but i hear that can be tricky because i have to essentially cancel my trip and rebook. the csr i talked to recently said that they are working on an enhancement (which is a phrase that i liken to the line "the check is in the mail") that will allow them to upgrade the existing reservation.

any insight?