Add Promo to Existing Reservation- Lose FastPasses?

[TW22]

I have a room only reservation for Sept. 7th-12th (booked directly with Disney). I purchased my tickets separately through Undercover Tourist. I can now save ~$200 on my hotel reservation with the new room only discount. Can I have this promo added to my existing reservation or cancel my reservation and re-book? What will be the impact on my fast passes? I would rather miss out on the discount than lose the fast passes.

If I can get this discount applied or rebook without losing fast passes, do I need to call Disney or can I do this online?

** Thanks in advance for any help. This is my first time booking a Disney trip and the process has been overwhelming .

 

[DisneyWishes14]

You can try modifying your reservation online. If you can't do it online, call and ask if you can modify it to apply the new discount. Modifying your reservation will not impact your FP+. There is no need to cancel and re-book a room-only reservation.

 

[TW22]

You can try modifying your reservation online. If you can't do it online, call and ask if you can modify it to apply the new discount. Modifying your reservation will not impact your FP+. There is no need to cancel and re-book a room-only reservation.

Thank you so much! I was able to do it online.

 

[dkbnyc]

cancelling your reservation will also cancel your FP, but modifying will not. I did it this week directly through Disney

 

[AngiTN]

cancelling your reservation will also cancel your FP, but modifying will not. I did it this week directly through Disney

Nor does cancelling a reservation and rebooking right away. Completely cancelling and never rebooking is the only time they get cancelled. Some reservations just won’t modify online and I’d rather call just about anyone else than call Disney. So I often just cancel and rebook, anytime I can’t do it online myself.
Another example was booking a bounceback and then wanting to get an AP discount instead. You can’t ever modify BB online