Joint Family undivided Properties Matter

Dear Sir/Madam, I am from Bihar and live in so called Joint family (By Law No Document available for proof). My Grandfather has 3 sons, 1st (Bade Papa-Elder Father) and 2nd (My father) had passed away and 3rd (Uncle) is alive. My father was the Karta of this Joint Family. He had the wholesale cement shop and agriculture lands which my father had bought but due to some reason few of the lands he had bought, he bought on Bade papa’s Name and on Bade Papa's Sons’ name. All financial matter was getting managed by my father. Even education expenses of Bade papa's sons had been paid by my father as that time he was only the source of income in our joint family. Bade papa sons and Uncle are well settled and they have bought lot many properties (Commercial and Residential) in different-different cities. There is a discussion going on to divide the properties. They (Bade Papa's sons and Uncle) are asking to divided all the properties (Few are on my Grandfather's Name, Bade father's Name, Bade Father's Sons' Name, My Father's Name, Uncle's Name) in 3 equal parts for Bade Papa, Papa & for Uncle. The lands which are on Grandfather's Name we inherit and rest all are bought by my father (but all lands are not on his name). Our point is that divide only inherited lands in 3 equal parts and leave all the lands bought by my father else divide everything (Inherited, bought by my father, bought by Bade Father's sons and Uncle) in 3 equal parts. They are not ready on this point and now they started selling lands without taking consent of other shareholders. They are threatening us that whatever lands are on their name (Elder Father's Name, and his sons' Name, Uncle's Name), by law ,are going to be their properties. Still nothing is divided and I am not sure what is the chance of winning If we knock the door of court? 1st thing what we want to do that no one should sell land until it divides? Need to know all the processes to stop them in selling the land immediately? I request all senior and experience advocates to guide us. I appreciate and respect your valuable times. Thank you in advance.