Tomorrow there's going to be this bratty girl in my group that I teach at Vacation Bible School. What do I do?

Okay, well, my friend and I are volunteering at our church to help run Vacation Bible School (I'll call it VBS.) Well, my group is very peaceful, because there is this one girl that was absent today. Let's say her name is Amelia. I don't mean to be mean, but all of this is true. Amelia is this kind of bratty, take-charge, and bossy 4th grader. She's nine, I'm thirteen. I just know she's going to try to take over my group that I am in charge of! What can I do? Because I don't want to get bossed around by a nine-year old. Please help.