My sister's father in law refuses to give them anything in the property

My sister's father in law was never in good talking terms with his son when we got my sister married 10 years ago. This fact was unknown to us at the time of her marriage and it was an arranged marriage.My sister has always been a housewife and has a daughter who is 9 years old. In the initial years of her marriage , her husband used to falsely show that he is working with his father but after around 2 years both father and son had a dispute and her husband was left with no work. He then did a job and after few years left it and from 4-5 years he is doing nothing. My sisters father in law now gives them 30000 per month and all educational expenses of his granddaughter. He has 2-3 good properties in delhi and is making rental income of around 10 lacs a month. The other part of story is that my sisters father in law is head over heels with his daughter. His daughter and his son in law ( both are into service sector) are living a financially well off life with a great support from sisters father in law. Now the problem is my sisters' in law dont treat her with respect. And refuse to increase their pocket money. Her husband is not ready to work. The family relations in the in laws house are bad. And yesterday only her father in law told his granddaughter who is just 10 years that she should try and make good relations with him and her bua ( sister in law). He will make her bua as her caretaker and not give anything to her mother and father. My sister coming from a small town has always been naive and her father in law is highly arrogant and egoistic man. What can my sister do in this and what are her and her daughter's rights?