And SIL did nothing. Well, she picked him up and cuddled him so that he calmed down after DP told him off. She never tells him no, and hes been allowed to get away with quite alot as he was the first grandchild. DP was really upset and had a word with MIL and other SIL once they'd left and they stuck up for the toddler because hes just a baby etc, he doesnt understand. He wasnt having a go at the toddler, he was passing comment on his sister and her laziness. (Little boy was hitting the playstation with a hard toy teapot that day too, and she didnt say a word)
Im sure this will kick off but Im sure by now he should be learning No. And that babies arent for punching.