Appreciate the reply. I should have made clear that I understood the implication of posing as if you intended to actually board.
My intended gist was handing the bp over, saying my travel plans have changed, but I'd like mileage credit for the itinerary that I'm not using (and which has insufficient residual value to re-ticket).
Just looking for a reality check. I heard of such a thing a decade (or more) ago. But I'm pretty sure that game is over. Bottom line: no bis, no mileage credit.