Illegial house occupancy

Hi Sir/Madam, My father had an elder brother and has a younger sister. We had an ancestral house. Upon my uncles compulsion (fathers brother)…they sold that house and distributed the money equally. My uncle was a sick person, so he told my father that he needs that money and my father in his own saving bought a house. He allowed my uncle and uncle’s wife to stay in that house. My uncle has no children. My uncle lived in that house for 5 years and he died in that house. After that, my father let my uncle’s wife to live in that house. After 11 years in 2020, she filed a civil case claiming that the house was bought from the money obtained from selling ancestral property and she claims that the house should be sold and she needs to get full money. My uncle’s wife died in 2021. After her death, we are waiting for the courts order to dismiss the case. It’s been more than 1.5 years now and in this meantime, the daughter of my father’s sister and her family who were with my my uncle’s wife during her last days have illegally occupied the house (registered on my father’s name), they r refusing to vacate and now she (daughter of my father’s sister) has written a petition to the court that my uncle’s wife is her ADOPTED MOTHER (since she got the death certificate) and she wants to continue to the case. My uncle’s wife has her brothers and sisters (all are alive). She threatens to commit suicide if forcefully expelled from the house. Now she has sent the notice only to my father. It’s been 5 adjournments now. She hasn’t sent the notice to me nor my sister (as the case is filed against m father, me and my sister). Our lawyer is saying since she has not sent the proper notice to all involved in the case even after 1.5 years, it will automatically be dismissed by the court. How far it’s possible? He his asking my father to appear in court every time And kindly explain about the ADOPTED mother claim. My uncle’s wife has clearly mentioned in the case file that she has no any children. Only by getting a death certificate, can someone claim that they have adopted them? Please explain. My father did for the goodness of his brother. Now he is going to the court continuously. What we have to do now?