Originally Posted by transpac

In similar circumstances, I have been asked how I planned to support a gate-clearing waitlisted first segment upgrade. Both times I pointed out that I had used a SWU to upgrade, hence I was holding C boarding cards for downline segments. The first time they pulled a e-CR1, which was quickly replaced without any intervention on my part. The second time they could see that an e-SWU had been pulled for the full itinerary.

Just mention that you already used a SWU, show them your SFO-NRT/NRT-SIN C boarding cards. Even if they pull a CR1 or 500 milers just take the boarding card and clear up the problem later.