Partition of property

Greetings sir, This is Mohammad Javed Ansari from Siwan Bihar: We have a residential and agricultural property with a mutual division between my Garand father and his brothers (total Five brothers), the mutual portion was done many years ago, I think more than 45 years ago. Some of the property is ancestral(belongs to the great-grandfather/pardada) and rest of them are registered under one of brother of my grandfather But unfortunately no paper work was done for this partition and now all five brothers including my grandfather has been already dead. Regarding the residential plot, each brothers of my grandfather had already built a house on their respective partition of residential plot many years ago ( more than 40 years) I would like to highlight that where we are presently residing now, this plot is still registered under one of brother of my grandfather exclusively. Now, indirectly my cousin brother giving us a threat that all the property belongs to my Dada ( brother of my grandfather whom the property is registered) is my property and I will capture very soon. I am seeking a advise to resolve the situations arise in the family. Please help what shall we do now. Thanks and Best Regards, Please contact me on [deleted]