Here is a website that has the Food Monitor Handbook for family daycare's and on page 24 there is a section about milk substitutions. I know it's not about the wheat/gluten question, but if you read through it, it may answer some questions about food and drinks.
It also says your state agency will decide which substitutions fit the requirement (for milk). I thought it would be the same for everyone, I guess not.
http://www.fns.usda.gov/sites/defaul...ring_Homes.pdf