Property law for the 2 sons in which one died and one sold out his portion to other.

Hi, My case is stated below. One mother has 2 sons was educated enough and got the government job. Other one was ok in the study so got the low-grade job.. Their mother divided the property into two parts ... Mother has 2 flats one are is 98sq ft. And other one was of 110 sq ft.(E.g ) as I do not know what to say warg gaj in English... Division was like this .. youger brother got the 98 one portion and 52000 rupees extra 30years back. & Elder brother gets the 110 one portion at that time. After some years both of the brothers got the job.Elder brother got married and got the working wife. Younger one was not ok with the financial condition. So younger brother's wife got jealous with elder borhter and his family income. Now after some days Elder brother fell sick and passed away. his wife Also got retired from the official post and was looking her family ...Her Sasu ma and her children ... After some years younger brother came to the house and took his mother with him to his house for a living. Some years passed and after that elder brothers' family left their resident and city as well, locked their house, and got settled in another city for their job. Behind this scene younger brother sold his assigned 98 one portion with the help of his mother. Now as the Mother's age is 92 years . Elder brother's wife taught to get the property transfer on her name and want that Her sasu ma write a will related to the property . Now the issue is this, as the younger brother has got the small portion and 52000 Ruppes cash. He sold that portion which is assigned on his name. Now demands the portion in the Elder brother property 110 one. And not sending her mother for the signature on the will and locked his house so that no one take the Mother for the signature on that will. Now he needs the some % share from that property as well. Please guide me in that case what can we do and legal action can we take against the younger brother and the family.. NOTE: 30years back mother, and both his sons signed the FAMILY Agreement on 10 rupees stamp paper.. BR