Originally Posted by
MSPeconomist
Depending on your fare construction, the same GUC should also cover upgrading the AAA-AMS segment on KLM if upgrade inventory is available.
When I changed from KL to DL marketed flights, I had to pay to re-fare it. The KL marketed was less than the DL marketed equivalent. This was a new experience to me, but the cost was fairly insignificant and I had HUCA'd a few times and gotten the same response. Re-faring just the AMS-SFO leg was, surprisingly, a few hundred less, and the initial leg is <2 hours, so I didn't want to bother paying anything for that leg.