As long as the sofa is not the newer type where the cushions don't come off the sofa. That's what they have a BCV. I think that is what they have at BWV, too.
The "daybed" in the dedicated Studio Plus is about the size of a crib. It's basically a deacon's bench with a thin cushion on it.
The Studio Plus cannot be guaranteed or even requested. It's just the luck of the draw.
If the kids won't sleep together, ask which one wants to stay home on this trip. Or, they could share the double sleeper sofa this time. Unless mom and dad want to split up for the stay. Mom with daughter, dad with son.