My friend ran into a similar problem. He's leaving tonight on HNL-LAX-LAS.

HNL-LAX is CO and LAX-LAS is UA. As a CO gold, he told me he was getting UDU'd 100% of the time from HNL-LAX.

He was already UDU'd from LAX-LAS a few days ago.

This time, he went to check in 24 hours before the flight and it he couldn't check in. He called CO and they said although his reservation is still in the system, it's frozen and there's nothing they can do about it. He was told to show up at the airport and take care of it there.

Oh, and he was also told that because of this, there's no chance of a UDU for the HNL-LAX segment.

I've never heard of such a thing happening and now I'm really reluctant to book a mixed metal flight.

Thoughts?

Finally, what is the process for upgrading a mixed itin? If I use a CR-1, can I do it on-line?