Well, my two friends are flying from Spain to BKK and returning from PVG back to Spain. They are also flying one way BKK-NRT and after a few days will be flying one way BKK-PVG. That's why the need for the one way tickets, because of the open jaw return on KLM/Air France.
$426 on NWA? I did not see that fare for April 25th on the internet.
The fare I listed was on China Eastern.