Just checked a bag at AMS on an FB award booking. The check-in agent was able to effortlessly change the FFP number to my AZ number. That was never previously possible on several other attempts at AMS over the last 18 months.

Anyway, she reprinted the boarding pass but there was no indication of Sky Priority...the first time this designation has failed to appear on a KLM boarding pass when using my AZ number. Whether this is a quirk of the system and having initially checked in as a bog-standard FB Ivory, I don't know. She also did not apply a priority label to the bag tag.