Hey there, Victorian!
I am the youngest of four, and it seems like one of my siblings is always either deciding to join our vacation at the very last minute or having to cancel without much notice.
Victorian, I am happy to tell you that you will be able to remove your sister from your
Walt Disney World Resort vacation package.
What you will want to do is to log into your
My Disney Experience Account and click "My Plans." Next to your resort reservation, you should see an option to "Modify or Cancel" your package. Here you will be able to remove your sister as a member of your traveling party. The total balance due on your account will be adjusted accordingly.
Now, if your sister purchased her
theme park tickets and
Disney Resorts Collection hotel separately, as opposed to through a vacation package, you will have to remove your sister from the hotel reservation on your My Disney Experience Account. In this case, her theme park tickets would be non-refundable.
I hope that this answered your question, Victorian! Please come back here if we can help you in your planning adventure.
Sarah B.