[Since my question has nothing to do with actually getting an international upgrade, I hereby apply for a waiver from the $1 penalty for this question :-)].

I have a paper ticket in coach on NW for NRT-SIN. I have secured an upgrade from CO using CO miles for both segments, and will be receiving upgrade certificates in the mail.

The big question is, how do I get this upgrade processed? I have received 3 different answers from CO reservations:

1. Turn in the certs with the ticket at the NW counter on day of departure only.

2. Turn in the certs with the ticket at a NW ticket counter, on day of departure or anytime prior for reissue.

3. Turn in the certs with the ticket at a CO ticket counter only. The certs and old tickets will be collected, and new tickets in NW business class will be reissued on CO stock.

Does anybody know what the actual answer is? As soon as I receive the certs, I will go to the CO CTO and try to get this done, and see what happens. But, I'd feel more comfortable if someone with experience with this type of transaction could tell me what the real answer is. Of course, I'd much rather get this done one way or the other while still in the US, rather than dealing with a potentially unsolvable problem at the NW counter at NRT.