Regarding father's own earned property

My father had 2 wives. They were real sisters.Now no one is alive.The elder one gave birth to 4 children and the younger one to 6.Both the sisters got some land from their parents .My 1st question is whether all the children have their share in that or only daughters can claim their mother's ancestral property.(2) my father has earned some agriculture land and other property i.e.houses etc his own.Certain part of the property he gave to his children before his death and some he kept in his name.After his death my elder brother claimed/told me that father has written all the property in his name as i was staying out for my job .He had never shown the will to me.Now my elder brother is no more.he died in2007.After his death his 3 sons had captured /grabbed that property.Whenever i am trying to ask they start fighting and telling that tthey have the will but never showing us.I want to make one thing clear that both the sisters were staying separate.I am the last son of the elder one .We are 2 brothers and 2 sisters and the younger one had 3 daughters and 3 sons.As i was working outside my brother and my elder sister who is unmarried and was staying with my brother's family played tricks on me . She(my sister) wrote all the property of my mother in her name and supported my brother to grab all my father's property in his name.i want to know (!) After my brother's death; who claimed that my father had written all the property in his name ;this property will automatically transferred to his children (2) who will be the next heirs (3) can we i.e me or my children claim it if it is yes what is the procedure (4) Can my younger sister or her 3 sons can claim their share in my mother's and father's property (5)Can my mothers younger sister i.e.my second mothers children have their share in my fathers property .My mother died in1992 and father in 1994.I got retired in 2012.After that when i planned to settle down in my native place i came to know the facts. till now they never shown the will to me .They always fooled me by saying that you will get your share when you will come back. We always trusted them and allow them to use that land for agriculture.Is there any way out to get our share.They have already started selling that land and property without the consent of other legal heirs Please suggest some solution.WITH REGARDS