You can update your reservation on the Disney app. Or just tell your server when you arrive. You won’t be charged a fee as long as someone shows up for the reservation.
You can call the dining reservation line but keep in mind you may have to cancel your original reservation and reserve again .If the day is the reservation is Friday thru Sunday you may be out of luck because the processional dining package is very popular those days. Sugestion Skip the dining package and go in to th stand by line for the last show of the evening. You will have a 70 to 80 percnt chance of getting a seat. It may not be the best seat but you are not paying for a overpriced dinner just to get a reseverd priority seat. I always done this and it works.
Have a look on the Disney app
Call Disney dining reservations line.
I will call and talk directly to the people at the restaurant
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