Thankfully I intervened before my 3 year old proudly fed him the second half. He proudly told me that baby brother doesn't want milk anymore as he eats food now! 
I only left them alone for 2 minutes with baby in his bouncer and my son sat at his table eating pudding!
I hadn't thought about weaning yet but I've got a chocolate faced baby who is extra smiley and licking his lips.. not sure carrot purée will be popular after his introduction to solids 😂