False allegations and dowry case on husband and claiming maintenance

My brother married a divorcee on 15.04.24. She stayed with our family for about 2 months (from 22.4.24 to 27.6.24 - visited her parents for around 3 weeks so the net stay in my parents house was only about 40 days). She left the family claiming she's not comfortable to stay with my parents and came back with a big gang of about 15 people on 18.8.24 and created a huge ruckus infront our house, defaming our family in the entire neighborhood. They even tried to physically assault me and my mother. Then the issue went to police station multiple times, and it was decided to go for divorce each time. Now she has made false allegations of assualt and DOWRY on us and sent a notice claiming monthly maintenance of 30,000/-.(Please note this marriage was entirely funded by my father which was 5-6 lakhs and the bride's did not spend a single rupee owing to their financial inability) She had followed the exact same plan in her first marriage too and claimed compensation from them. So it appears their family is doing a pure monetary business out of this marriage. My questions are: 1. What are the laws on claiming maintenance? On what grounds can we contest the case and deny to pay the same. 2. Can we file a counter case for the false allegations of assault and dowry? 3. Can we file a defamation case for defaming the family in the neighborhood where my parents have been living for the past 32 years and claim compensation. Please help and guide how can we go about this.