you know on second thoughts ,i think maybe you should approach him and have it out with him, maybe that is what is needed and he will stop, he might not even be aware that you feel or think this way, it may well be that it needs to be pointed out to him, and he might get a reality check and realise what he is actually doing, i am glad the little boy seems to be unware of it,i hope it stays that way, as it certainly is not good for him, he sounds like he is being picked on by your BIL and for no real reason what so ever, good luck.