Here's a hypothetical situation: Traveller is flying Europe-Hawaii. OW upgrade inventory (25SS) using miles is not available. Traveller has requested sticker upgrades for mainland-Hawaii portion.

What if the sticker upgrade portion clears AND there is standby/day of travel upgrade space available for the Europe-U.S. leg? Can the traveller pay the last-minute $75 fee and pay for both upgrades using the 25SS?