Yo Ho, Yo Ho, Benjamin!
You are as welcome as can be here at planDisney. Thank you so much for your question. How exciting that your magical Disney vacation is just around the riverbend. Our family just came home from Disney in March, and like you, we stayed in a 5th-sleeper at a
Disney Vacation Club Deluxe studio. Benjamin, typically, if the room allows for a 5th person, Guests can request a blow-up mattress upon arrival (subject to availability). We have also traveled with our own, but that is extra luggage you may not need. The only question would be the space in the room and if there is room for the blow-up mattress to fit, without blocking the exit in case you would need to get out in an emergency.
You can certainly call Guest Services when you get to your room to request one, and they may be able to accommodate you so that your kids don't have to share a bed. However, since you don't have a 5th person listed in your room, they may reserve those for those Guests. But it's always worth asking!
You can request any additional supplies you need for your Villa by using the
"Hey Disney" tool in your room (it is the device with the Mickey Ears). Just say, "Hey, Disney, show me what you can do," and use the prompts to request what you need. The only exception is the blow-up mattress. For this, you need to use the phone in your room and call Guest Services. But if they can accommodate, like Lightning McQueen they'll bring it up faster than fast and quicker than quick!
I hope this helps you, Benjamin! If you have any further Disney vacation planning questions, stop back here to see us, and we will be so happy to help you.
Magically Yours,
Keri