No they'll just take your word
No you don't have to show anything just let them know that's what type of seat you need they usually ask you to pick your row anyway depending on the number of people in your party
You have to be careful because some of the handicap setting are for wheelchair only its not an actual seat
You have to pick your seats online or on the screen at the ticket booth so you can pick them there. They are clearly mailed out as handicap seating. Very easy.
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