Cut and paste from our resident expert JPVonDrake:
If you are more then 45 days prior to arrival on a vacation package, Walt Disney Travel Company does not charge a cancellation penalty. You would get a refund of the amount you paid minus any NON-REFUNDABLE components such as Vacation Insurance or select Airfare.
You may also modify you reservation anytime up to 45 days prior to arrival without any Disney change fee based on current availability and the deposit paid would move to new travel dates. Again, if non-refundable components were included change fees to these items may be charged by those providers.
Cancellations made 44 to 6 days prior to arrival will be charged a $100 fee. Cancellations made 5-0 days prior to arrival will be charged a $200 fee. Any changes made within 44 days prior to arrival may be charged a $50 change fee if the change results in a lower package price. If any change is made within 14 days of arrival a $10 special handling fee may be charged to cover overnight mailing of new documents to your Resort.
The only portion that would be refunded are her tickets, dining and the surcharge per night for an extra adult in the room [unless you all booked separate rooms]. So if you booked and divided the cost between the four of you, the remaining three will have to pitch in to make up the difference between what Disney refunds and her quarter share [less any penalties if you're within 44 days].