There should be no reason why you can't use the new PIN. They may need to change the lead guest on the reservation or even perhaps need you to book a new reservation and cancel the existing. As long as there is availably under the new PIN code you should be able to work it out.
There are usually only a couple of reasons you can't add a PIN discount to an existing reservation
1. The dates of your trip don't align with the PIN availability exactly or
2. There is ZERO availability at the resort or room category where you are booked currently.
In the case of # 1 arrange your trip differently or in case of # 2 .. you would be required to change resorts and/or room category to take advantage of the PIN.
Our Authorized Disney Vacation Planners are here to provide personalized, expert advice, answer every question, and uncover the best discounts.
Let Dreams Unlimited Travel take care of all the details, so you can sit back, relax, and enjoy a stress-free vacation.