DS loves to play with DD but recently he's started to punch her and laugh when she wails - I've told him off for it (i.e. got down to make eye contact, held his arms and said NO! firmly) but he continues to do it. I've asked DD to just ignore him when it happens (i.e. not to make a noise or eye contact) so that he isn't getting a reaction but it isn't working.
She's getting really peed off with it and I wondered if others had experienced something similar and if so, did it last?!