Maintenance

Hello Sir, This is about my elder brother. He is been marrid for 10 years and they have son of age 9 years. Last year SIL fought with brother and my mother. She was not doing anything at home. All household work and kid's study was taken care by mom. She did nt give her phone also to kid for attending classes because she wants to talk with her friends.Kid's attended online classes using granny's phone. She kept on fighting. We tried to resolve it by mediator.But she left the house with her brother's. In between brother tried to talk with her and her family. But they are admant. Neither she returned home not replied positively to husband's call. It's been 7months now she deserted her husband ,kid and home. Today we have received notice for maintenance. She does nt want live with husband. But she wants maintenance. Brother is compromising looking at son. Can she claim maintenance if husband is ready to live with her? Can she get maintenance of she denies to stay with husband? She has put false case under domestic violence. In the notice she has asked only about maintenance , she has not asked for custody of kid. What legal action we can take to safeguard brother and mother's life ?