Divorce problem of my Father

Hi, I have a problem to share in this portal. My father is retired from Airforce. When he was on training, his first wife developed relation with my father's elder brother. My father came to know and raised the issue in panchayat where my father's forst wife refised to stay with my father and divorce in panchayat was done with mutual concent. My father gave all his ancestral property to his first wife and son as maintenance foe which he has written proof. Later he got married to my mother in 1983. My father tried to keep his 2 son's from first marriage with him but his first wife refused to let them stay with my father. Everything was going fine till 1993 when she filled a written complaint against my father in airforce that she is the right ful wife. My father with help of an Airforce lawyer filed a divorce case in Ludhiana court as he was posted in Ludhiana at that time. No one from his first wife side appeared in court after getting suman. Court awarded divorce to my father on 1993 after his first wife gave written concent for that. My father retired from airforce in 2009. And he was living a peaceful life in delhi but suddenly one day in 2017 his first wife, her elder son and her brother came to our home and started claiming thier right in property and even denied divorce of any kind. The property where we live is in my mother's name. We filed a case aginst them for forceful claim of the property in Dwarka district court. After few days she filed a case in Ludhiana court challenging the divorce that happened in 1993 saying that she didnt received sumon. Then she filed another case in Jahanabad district court claiming maintenance. And now third case in Ludhiana district court again claiming maintenance from my father and even asking my father to pay for the lawyer as she dont have money to fight the case. We are in immense mental pressure and my father in this old age is running all around delhi, ludhiana and jahanabad for the case hearing. Kindly suggest what can be done in this cas. Thank you