Hi Michelle!
Welcome to the Disney Parks Moms Panel! I absolutely love
Disney Gift Cards; not only can they can be used anywhere at Walt Disney World Resort to buy just about anything, they can also be applied towards a vacation package or a
MagicBand balance!
While there isn't a place to add Disney Gift Cards to your My Disney Experience Account online, you can use your gift cards to pay off some (or all!) of your pre-vacation balance that is due upon your arrival. I've done this before where I handed over all of my gift cards to the helpful Cast Member at check-in, but you may also call the Resort Hotel Reservation phone line at (407) 939-1936 and pre-pay that way.
If you're wanting to use your Disney Gift Cards for souvenirs, snacks, or
special experiences from the Enchanting Extras Collection like a tours or a spa day, you're more than welcome to use your physical cards. Or, if you're a guest of a Walt Disney World Resort Hotel you may charge those things back to your MagicBand where you can pick up the balance with your Disney Gift Cards later. During your resort vacation check-in you'll provide a credit card that will link to your MagicBand, but these charges won't hit your credit card until you've either charged a certain amount or you check-out, whichever is first. You can pay down your charged balance with your Disney Gift Cards by stopping by the front desk every few days, which will reset how much you've spent towards that charging limit before that balance officially hits your credit card.
I hope this helped, Michelle, and We'll See You Real Soon!
~Kristen