I've attached two factsheets ("A Day of Added Sugar" and "Chocolate Milk and Added Sugar") that we developed to make the case for why the added sugar in flavored milk contributes to the overall excess of sugar in our children's diets. In addition, here is a link to our Nutrition Standards Relevant studies page:
http://www.ruddrootsparents.org/nutrition_standards.aspx?print=s. You will find that there are useful scientific data that explains why too much sugar in one's diet is harmful to health.
Please let us know if we can provide you with additional information. And if this proves helpful, please tell us about your experiences - how you tried to make change and how it turned out!