Dowry harassment case in police station

Sir , My brother in law was blind from his childhood. He cheated us and married my sister . After marriage he informed my sister he has only one eye from the childwood. My sister was shocked that time then she convinced herself and started living with him. One day his mother asked us to pay 10 more soverigns of gold as a dowry my father denied to pay. From the day onwards his mother started harrasing my sister but she continued to live with her. After 1 year a child was born to my sister but in my brother in law family no one was interested for the child and started harrasing her . Finally my sister came back to our home and waited for my brother in law would take her back to his home but he didnt come. We all went to his home asked him to join with my sister but he denied to live with her. Today he has sent a lawyer notice to my sister asking to dissolve marriage by mutually. So shall we file a dowry harrasment case in police station? Luckily my sister has capture photos of her mother in laws diary. In that she wrote my sister didnt bring any money like that.