YOU: Excuse me, would it be possible to switch/change seats with someone? My wife and I would like to sit together.
FLIGHT ATTENDANT: Certainly, sir. For now, please take your seat, and once the plane takes off, I'll help you with that.
YOU: Thank you. Could you help me put this bag in the overhead compartment?
FLIGHT ATTENDANT: Sure. There you go.
YOU: I'm sorry, I think you're in my seat.
OTHER PASSENGER: Oh, let me check my boarding pass. Yes, I'm sorry, my mistake.
YOU: No problem. That happens.