I stand corrected. I think......! Generally speaking, when we fly Business or First we’ve purchased revenue tickets although we have done upgrades a few times, too, when they were easier to do. Not really all that certain about their protocols regarding FF tix. Truth is, neither of us drinks and with the exception of a few flights to Hawaii most of our flights are 3,5 hours or less so the need for those big seats isn’t really a deal breaker for us. Always nice but not a deal breaker.

The only time there was ever an issue for us we were politely asked by an AA Supervisor at check-in in SXM to give up our seats to a high ranking FF with supposed health issues and AA was very good to us for agreeing to do so.

They put us in a three across row with the center seat blocked and provided us with drinks and dinner as well as cash vouchers for accommodating their needs. Worked for me......

But I still think when the OP paid for that seat they’d be hard pressed to seat someone else in it without his okay. That’s my story and I’m sticking with it! 😊😊