Originally Posted by Grouchy

For flights departing from AMS you check in with KLM, even with a 006 issued ticket and a Delta marketed and operated flight. There is no day of departure cash upgrade program that is selectively offered during online check in, there is no waitlist and they don't fully manage the process as only KLM can clear that DM's GUC. A DL agent can't..

If Delta wants to optimalize both DM satisfaction and extra income or mileage burn they best cut KLM out of this process.