Juice is extremely important. Especially if you are not giving vitamins. It doesn't ever happen anymore, but remember scurvy? That was from lack of fruit. Please do not be alarmed, but that is how I remember fruits and veggies.
If you have the "energy" you can make your own juice from fresh fruit. Otherwise Juicy Juice. Juice Huice contains 100% fruit juice. Also, children do need a certain amount of sugar in their diets. Just look and see how much they are getting in the other foods they are eating. Juice is healthier, it is a natural form of juice than white table sugar. I know the program you are talking about WIC we have it here in TN too.
I am not saying that the youngest is following the oldest in the way of loose stools, but it is possible.
The liquid form of vitamins is for INFANTS, your children need need vitamins whether through foods or suppliments.
Let me know what the docs say tomorrow. Just remember to ask if water and milk are enough.