My elder brother's wife is harassing him by humiliating him without any reason

Dear Law, Me and my bother's family stay together : i have my wife and have 2 children and we all stay together in 3 bedroom flat. as my wife went for conceiving My query is related to my elder brother and his wife : it was his and her second marriage to both of them - they got married in 2016 had a 10months old little girl - to my observation my bhabhi ji was behaving differently after the baby was born and everyday one or the otherway she is trying to harass my brother in terms of saying ur not doing this and that. he is working in a small private limited company and its really a stressful work even after coming home he has to work at home doing house work as well though we have a washing machine, house maid to clean utensils, sweeping and wiping whole house except for cooking even that he does and i too help in doing some of the cooking - Even when he is at work place she calls him and says baby is crying come home and keeps some or the other argument with him - he is confused and doesn't know what to do keeping his previous divorce experience in mind he is dying inside and out not even able to express us anything. she says or wantedly brings some argument for unnecessary things and i think somebody is wantedly guiding her or provoking her to do all these things - as it was their second marriage i feel unsecure about his life again as on his first marriage they made some false allegations and threatened for a ransom amount from family and sometimes feels unsecure about his life - how to track what is exactly happening with her and is she following someone to do all these and what intentions has she got. If marriage life is not her cup of tea why to get involved - During Engagement talks also when asked about her previous marriage dispute they said we dont want to know what happened in your past and we also dont want to tell our's is what they said. i also feel sometimes that she had some mental disorder which their family didn't let us know. Somebody who stays/lives with her for a month of two would understand her nature - Maybe this nature could have been one of the reason for her first divorce. I as a brother feel insecure to his life one more disappointment in his life will effect his whole life so can i make a prior complaint on her to jurisdiction - so far i didn't even tell my brother about this but i want to save my brother from this mental torture. Please guide me and can i actually ask him to keep a Camera at home for his security purpose so whatever is happening will be recorded