Hiya Sarah!
Welcome to planDisney! First, Happy Early Birthday! Celebrating your special day in Walt Disney World just sounds like perfection!
I reached out to the friendly Cast Members at Walt Disney World and found out that you cannot have two reservations at the same time. You will have to check out of one Walt Disney World Resort to check in to another. If you wish to book a one-night stay then someone who is not on your existing reservation would have to make the booking. May I also suggest shortening your stay at
Disney's Pop Century Resort and adding a stay at
Disney's Grand Floridian Resort & Spa? This way you get that one night but it will just be a little easier.
Bell Services can be a great help with moving luggage. Just let Bell Services know at Disney's Pop Century Resort know that you have a reservation at Disney's Grand Floridian Resort and they will handle getting your bags to your new resort!
If the room booking doesn't work out there are still ways to enjoy Disney's Grand Floridian Resort & Spa by checking out the "& Spa" part.
The Grand Floridian Spa is open and ready to pamper your entire body. Leave refreshed and rejuvenated and consider a lovely dinner at one of the many beautiful and delicious
restaurants on this Resort property. I would recommend
Narcoossee's in the evening while watching the
Electrical Water Pageant. Just thinking about it makes me smile.
I'm hoping this helps and that you have a magical birthday!
Let me know if you have any more questions as we are here to help!
Happy Planning!
- Nimmy