Originally Posted by
channa
The way I understand it is that the minute UA upgrades you, your ticket will be out of sync (normal for UA upgrades, but not normal for CO upgrades), and that you will no longer be eligible for CO's EUA as it will skip over you since you're ticket is out of sync.
MissKok had a trip last month (slightly different from the OP) that was:
1st segment ORD-HNL on UA,
connecting to
2nd segment HNL-GUM on UA,
connecting to
3rd segment GUM-MNL on CO
She upgraded ORD-HNL months before using a UA CR1, her OnePass Platinum number was in the record, but when she checked a few days before, she was not on the online EUA list for GUM-MNL. When she called CO the day before to find out why, they told her it was probably a glitch and she was definitely eligible for EUA. She didn't clear, of course, probably for the reason you stated.
In a situation like this, is there anything she could have done to get her properly on the EUA list for her 3rd segment? I ask because I am doing the exact same trip next year.