On our September cruise, we let the girls have the 'freedom' to go places as long as there were 2 of them AND we knew where they were going. We had a wipe off board in our room for notes, but we didn't use it much.
Mostly, the girls would just tell us where they would go and then we would meet up with them later.
I will probably be a little more relaxed in December since the September one went well. Of course, I have twins, so my rule is that they stay together and watch out for each other.
I did insist on being with them at the pool since there is no life guard (but remember, my girls just turned 11--your DD is older than my girls, so you might be alright with her being at the pool).
I figured the walkie talkie things would get lost and broken, so we didn't bother with them.
If Nat wants to 'meet' my girls early on and you guys plan to go onboard as soon as boarding starts, tell her to go to the Goofy Pool. They always go there first (and we just eat Pizza for lunch while they swim). They like to be the first in the Goofy Pool. We will probably be there until 1:00 or 1:30 when the rooms are ready.
DJ