I agree with Dave. Just be honest and ask. They're very accommodating and very attentive to the children.
On numerous occasions we've had families where their children are on the verge of the next level and would like to keep the siblings together - the staff has taken care of them without any problems.
I've had long conversations on several ships with the children's program supervisor since it's important for us to feel comfortable with the program and recommend it to our clients. And the one overwhelming thing that has always struck us is how much they sincerely care about the children and how hard they work to keep the children entertained. We've never gotten any complaints from any of our clients, which speaks volumes about how good they are. And, as we all know, if the kids aren't happy, the parents aren't happy. It takes a special person to do what they do day in and day out, and they have all my respect. I love children and they've always loved me, but that job is something I just couldn't do. So my hat is off to these wonderful people who do such a great job with the children.