procedure to claim share in property

Aoa
My grandfather died when my father was single and working in saudia arabia ,later he got married n had two daughters me and my younger sister,my father had 3 other brothers who are now deceased and two sister still alive ,since all brothers earned well hence no one discussed about there respective now when all brothers are dead n there children are alive and hardly in contact with each other we me and my sister thought about claiming our share but are not familiar with the process i dont want to ask blunltly frm my cousins least it offends them n they decline point blank so which institute or govt org can enlighten my query in this regard.