Ancestral property has been sold by second brother without consent and now not ready to divide left

My grandfather has two sons n one daughter (daughter has passed now). 30 yrs ago after verbal mutual consent agricultural property was divided half half. Two residential plots was there, one was 9 dhur and other was 36 dhur. My uncle went on the 36 dhur plot n left 9 dhur plot for us forcefully. As they were living in village and had some cattles we just ignored that time. Now uncle wants to make pakka construction (home) at full plot. When we object he said he is living there from 28 yrs so its their now. They have also made without pakka chhat construction at more then half of the area. Meanwhile he has also sold many agricultural land which was initially partitioned verbally on consent. Now he wants to take half part in each plots and dont wanna give share in larger residential part as well. He also says he will give share in larger residential plot if we pay for the construction which has been made there without our knowledge. One more plot was sold by my grandfather benefit of which was given to my uncle and no consent was taken from my father. We have doubt that my uncle may had signed on the paper at that time. Now kindly guide us how can we claim sold plot and how cantake my possession on all the rightful plots?