just that really. ds1 2.5 years old was great when ds2 came along but his behaviour with him had got increasingly worse and yesterday he but his finger and today he had left bite marks on his back. ds1 is otherwise a fairly well behaved boy. I just don't know what to do.
Is your 6 month old grabbing etc? Your eldest will now be seeing that baby can get in the way and gets annoyed hence biting.
My ds did this. We treated bites swiftly - a firm "no biting" and removed from the room. He could come back in and say sorry immediately, but any biting and we'd remove. We also gave him techniques for dealing with his frustration eg suggest he gve his baby sister something or called for mummy/daddy. We also give positive praise.