After the registration of the property in your grand fathers name the status of property change as self acquired property. If your grand father died intestate with out making any document regarding his shares all the children have equal right in his property. each of the person can get 1/4 share .
What is ancestral property ?
Property inherited upto 4 generations of male lineage (i.e., father, grand father, etc.) is called as ancestral property. The right to a share in such a property accrues by birth itself, unlike other forms of inheritance, where inheritance opens only on the death of the owner. The rights in ancestral property are determined per stripes and not per capita. This means that the share of each generation is first determined and the successive generations in turn sub divide what has been inherited by their respective predecessor.
What is not ancestral property ?
Properties inherited from mother, grandmother, uncle and even brother is not ancestral property. Property inherited by will and gift are not ancestral properties. Self acquired property on the other hand can become ancestral property only if it is thrown into the pool of ancestral properties and enjoyed in common. This is a matter to be determined on the facts and circumstances of the case.