Based on my knowledge it is okay. Howver the concern when doing that is because of the child does not finish his milk then we won't be able to know how much medicine did I take in.unless you are sure that baby will finish the portion of milk.
If possible not too. If really no choice then it's okay to mix. I did it a couple of times when my boy refused to take his medicnes.
Great news!
Hsieh Ni