This could be a really cool movie. I love Andrew Lippa.
...but really. No matter how much I love Kristin as a person, singer, and actress I would never believe her to be a high school student in a film. Same with Parker, but I think moreso Kristin. Short doesn't equal young. I think people will just watch it and see "Kristin acting" the whole time instead of the character she is supposed to be portraying.
--Like an odd exotic creature on display inside a zoo, hearing children asking questions makes me ask some questions too...--