Me and ds (3yo) live with my brother at the moment (due to abusive exP) and recently he's started to call him dad, I've tried to tell him that he's not his dad but his uncle but he still does it. My brother is obviously around a lot and does help look after ds but still he is not his dad. My brother laughs it off and says he'll grow out of it but I have to admit its embarassing as the other day he said daddy was picking us up from when it was actually my brother and me and my brother are obviously brother and sister (we look very alike iykwim).