I have the 4 RUC's remaining in my wallet applied to travel in April. We are on the wait list (transcons), but cabins show empty at present so we are hopeful.

I just noticed that my transcon tomorrow shows a few D1 seats left. I have not yet selected my Choice Benefit for this year, so I could pick another 4 RUC's.

I was thinking that it would be better for me if I could request one of the present RUC's, which are still in my wallet, to be applied to tomorrow's flight and then, if that goes through, I could eventually pick my Choice Benefit at a later date, so that the 3 remaining RUC's would expire later.

1) If I call now and ask to apply a RUC to tomorrow's flight, will they say "Nope. RUC's in your wallet are already committed to your Flights in april" ?

2) if this maneuver goes through tomorrow and I'm left waitlisted for upgrades in april requiring 4 RUC's total, but I only have 3 available, what happens next ?
Will one of my waitlisted upgrades be cancelled ?
Will they have the courtesy of telling me at some point that a waitlisted upgrade went through, but there is no RUC available so please provide one ?

Thank you for helping. It would be a pity if waitlisting for an upgrade in the distant future would make RUC's unavailable, but I had never thought about this issue until this morning.

I suggest you call. I'd also suggest you remove a RUC from a future flight, put it on tomorrow's flight and hope for the best. If it doesn't work it'll go back in your inventory and you can hold out to take your RUCs.

You can remove it from the later flight and have it applied to the closer flight. If you don't use it on that flight, it will go back into inventory.

You can technically have the same RUC applied against multiple reservations (though I don't know how willing the typical agent will be to do this). If it clears against one reservation then the other reservation clears, the second one will fail to reticket and stay in an error state until someone resolves it.

(At least IME.)