We had this a week or two ago when my son or daughter tried to remove socks from Gisgo when he had stolen them from the washing basket. Never any other issues like this but he did not like giving up a stolen sock to them! We went back to reasserting the "pecking order" and my son has been giving Gisgo his food every day (makes him sit and wait before he is allowed to eat) and they have both been playing with toys and removing those (by way of a reminder that they can take things away). Seems to have worked, I think Gisgo was just trying his luck at moving up the pecking order, and it did not take long to remind him! (he is just over 7 months and the kids are 10 & 7).