Property dispute. Howto proceed ?

My maternal grandfather bought a property in 1935. He was married and had one child (No.1). After the death of his first wife he remarried and had two children my mother(no.2) and my 2nd uncle(no.3). After his death in 1945 the property was passed on to my grandmother (1/3), and two maternal uncles (one from the first wife and the second from the second wife 1/3rd each). After the death of my grandmother in 1971 her part was divided into 2 equal parts (No. 2 and No. 3). so now the share was 1/3 (No..1) , 1/6 (No. 2) and 1/2 (No. 3). The 2 uncles later constructed a 2nd floor to the house in which they were staying and my mother was not. They also constructed another building behind in the same plot which they rented out. Now they are planning to sell the property so I wanted to know whether my mother gets 1/6th part in both the land and house (she did not stay there after marriage) or only the land. My uncle is saying that she does not get any part or consideration in the house. We are