This whole thing reminds me of an IAH-DEN flight I was on not so long ago....I am 1K sitting in 3D (bulkhead coach on 737)...my upgrade had not "cleared" so I took my coach seat in the first boarding group and started reading my book. Well the full flight is loaded now and there are 2 seats 2A and 2B open in first and the door is about to close. An FA walks by and I inquire as to the open 2 seats in first. She says that 2 GS pax have not shown and that she will get back to me after she responds to a call button in row 8. Well I can overhear the whole thing. A Pax who ID's himself as a 1P is sitting on the Aisle (8c) and is complaining that 2 POS's (Passengers of Size) have been seated next to him and that the combined effect is that he has only half his seat and no arm rest. He asks to be op-uped to 1st as the door is closed now. Stunningly, the FA says, I will fix this and takes the 2 POS PAX, both female, and seats them in 1st! This guy blows a lid! Boom! Capt. even has to come out. FA "apologizes" to me..."sorry"....anyway...1st in IAH-DEN is not worth much anyway...but that is not likely how the FA should have handled it. I called and wrote MP about it all...wow 500 miles added to my account! Anyway...stuff happens up there and the FA's do have authority to do non-conventional op ups.