Bava Batra 87: A Child Breaks an Oil Flask and the Storekeeper Is Liable (Maybe)

2 mishnayot! First: The case of someone who sells food and drink -- that is, oil and wine -- and the price rises or falls, and the seller or the buyer wants to renege, it depends where in the process of pouring it out for the buyer whether each can renege. If a middleman is responsible for the commodity, and a barrel of the goods breaks, he is responsible to cover the loss. Plus, the dripping of 3 extra drops, after the seller has transferred the buyer's purchase to him. Also, the second mishnah: Someone sends a minor son to buy oil with the particular coin to make the purchase - the kid loses the change and breaks the flask of oil, and it's a dispute whether the storekeeper is liable or not. Because wasn't it the father's goal for the storekeeper to give the child the oil and change? Or was that the storekeeper's independent decision?