My 1 yr old is transitioning from similac advanced to organic whole milk. rt now doing 1/3 milk, 2/3 form. he has gone from 1 bm per day to 3 or 4....

General diet change: The amount of fiber dictates a lot about the amount of stool you produce. The transition in his formula/milk intake is so minimal at this point with regard to amount of fiber, that i really doubt it has any bearing on how much stool production there is. More likely other changes in his diet to eating more fruits, veggies, grains and dietary fiber than an infant diet has led to the changes in poops.