If you start the Award ticket reservation without logging in, it's not there, and you get general availability. In that case, after the later login prompt, the passenger name is populated but can be changed.
OK thanks - makes sense because yesterday I didn't log into either of the two accounts until I was prompted so the check box wouldn't have shown - yet now, logging in with either account right from the beginning before entering the SkyMiles search menu, it still doesn't show. This is probably good in my situation, though, because your response indicates that since I wasn't logged in at the time I started the search, what I was seeing yesterday should have been inventory/availability for all pax and not just Medallions?
So - if I am seeing the inventory available to all pax (irregardless of status) if I search for award flights without logging in, then it seems like that would be the best way for me to search for my flights when the Medallion pax won't be flying with me - that way the search will not present options I can't actually fly. Then, when I get to the pax information page, I imagine it would NOT let me change the name to my own if I wasn't allowed to select those flights.
Thanks for helping me sort this out . . .it sounds like if I never have the chance to select the box claiming to be a Medallion pax then it will never allow me to select from "their" flight availability - so I should search without logging in (and not obsess over finding the box to check or uncheck) if I'm flying alone anyway.