Property issue

My father and mother died recently. There are 3 Sons and 2 daughters for them. All are married. •For Son1 –There are 3 sons (all are married) •For Son2 – There are 1 son & 1 daughter (married) •For Son3 - There are 2 daughters (.i.e includes 1 married daughter) •For Daughter1 – There are 2 Daughters(married) & 1 son (Major) •For Daughter2 (not alive) – 1 son (married). Her husband is alive and married again. Movable and immovable assets are self acquired by father & mother. Father had wrote a WILL in which some portion of agriculture land and tiled house were not covered. Agriculture land is there in mother’s name but there is no WILL. What are the rights for each one on the above? Are grand children have any rights? Don’t have legal heir certificate. Who are all the legal heirs? To register the above property in my name, from whom I have to get release deed. Thanks.