Since DS refused to drink pure cows milk, we are trying the sneaky approach on his pediatrician's recommendation. He had 2 oz of cow's milk and 4 oz of formula mixed together this morning. I was pretty anxious to see if he would drink it, but he drank it without problems. So I will continue to do this for a week, then increase the proportion to 50%-50%, then 75% cow's milk-25% formula, then all milk. That's the plan, anyway - DS may have something to say about it though.