Courtesy of Harav Yaakov Markowitz

Question: Mrs. A asked Mrs. B "can i borrow your make-up kit?" Sure, she replied! and as she entered her bungalow Mrs. B sent her 10 year old boy "b" with the make-up, to give it to Mrs A.

b saw "a" (Mrs. A 10 year old boy) next to his bungalow and said to him: "give this to mommy". A saw the kit and decided not to use it, she sent it right back with "a". The next morning, B asked A where is my kit? A said didn't you get it yesterday? B said no!
now the $200 kit is lost, who is responsible?

Answer: We learn in BB that one who sends his friend's object with a minor and it gets lost, the sender is liable, provide he simply "returns exactly what was sent" . Say R sends his boy to W with a pot, so that W fills it with rice. W took the pot filled it with rice and the boy broke the pot on his way home, W can say "you used this boy, so why are blaming me for sending him back to you!!" but if W gets beans and refills it with rice, he must pay for the rice---it is utter negligence to send a kid with rice!

In this case i suppose, if "a" received the kit outside the bungalow, A can say "i returned it, the way i got it" but if b delivered it "inside A's bungalow" although a was the one to bring it to mom-B can say "who gave you the right to return my object in a negligent manner?!