Hi Stacey,
Thank you for visiting the Disney Parks Moms Panel with your question!
I checked both on the website and in my Disney Vacation Club Vacation Planner, and it does appear that the deluxe studios at
Disney's Saratoga Springs Resort & Spa offer a queen-size bed and a double-size sleeper sofa. A one-bedroom villa at Disney's Saratoga Springs Resort & Spa offers a king-size bed and a queen-size sleeper sofa, so this would give your mother and 11-year old a little more space to sleep.
You could request to upgrade from the deluxe studio to the one-bedroom villa when you check in to Disney's Saratoga Springs Resort & Spa; however this would be based on availability. If you know for sure that you would like to upgrade now, I suggest that you contact your travel agent now to do so, since there is likely to be more availability now than on your check-in date. In either case, you should be prepared to pay for the upgrade.
I hope that these thoughts are helpful for you, Stacey. Please do not hesitate to ask if you have any further questions.