Right on the property of grand parents

If the property is acquired from the parents the person will not have any right to distribute the property as per his wishes. He has to go as per law. So he has to distribute the property equally to all his children. Now female children are also eligible for getting the property equal to that of male children.
But if the property is self-purchased or acquired by himself only he can distribute the way he wanted. No one can question him. He need not give his property equally to all the children and he can donate to outsiders also.
Your question is not clear about the property, whether it is obtained from his parents or self-acquired.
Based on this fact you can take the decision.

No one has a right to claim share from parent's property if the property is acquired by them from their own earnings and when the parents are alive. However if the property is received by parents as their ancestral property, then the grandchildren can have a share in that. However all these depend on various conditions and situations and we cannot give a blanket answer.

The sons/daughters should also be aware that they are not just entitled for assets of the parents , but should also own the liabilities of parents if they get their assets. Moreover children have the duty to take care of the parents in their old age and there are legal measures to 'recover' money from the children or their assets for maintenance of parents. Even the assets given to them by the parents can be made invalid and can be annulled and taken back.
So now it is not a one way rule.

As per the legal frame work of our country the property earned by a particular person can only be distributed as per his will or in absence of a will equally to his successors.

But an ancestral property is not considered in that way. In such a property all the successors are entitled to their share.

This is the basic philosophy used in property divisions and the necessary documents will be required to prove the category of a particular property.

The division of ancestral property is sometimes very complicated as there are many contenders for the same.

First of all your question is not clear enough to answer. What I have understood from your question, the answer is given on that basis.
According to Indian rule parents can decide solely how to distribute their property. They may or may not give their property to their own children. They can give their property to anybody, who is their relative or may not be their relative. They can give their property to any organization too.
Now the question comes if the grandchildren are able to receive the grandparents property or not. If the grandparents give their property to their son/daughter then the grandchildren got the property in the basis of inheritence. But if the property is not given to their father / mother then it is not the right of the grandchildren.
But in this case if the grandparents give their property to their grandchildren then they have right on it.

The author is asking about the process to get property via the grandchildren's right to a share of grandparents property.

There are two terms used in this context

Ancestral property: This is a property that has not been divided and has passed as a whole for four generations of male lineage.
When it comes to such ancestral property, the right for a share or an inheritance comes by virtue of legally proven birth.

Self-acquired property: This is property bought by an individual, for such properties, the question of inheritance arises from the death of the person who has bought the property.

With regards to getting a share of the property, this depends on two things
1. A legally valid will: Getting a share or not is dependent on entire what is written in this will.

2. Grandfather has passed away intestate (died without forming a will).
Then, it follows the legal course of succession
first, grandmother.
then, all the legal children
Many times, Only if all the class I legal heirs are taken care of and support them, then grandchildren can stake a claim for the property. This is not practical because at least one among the class I hiers would object and drag the case along.
For what, I understand, as long rejected son's parents are alive, the grandchildren cannot stake a claim.

We need proper details to advise specifically, I would suggest, make a list of the properties and how they have been acquired, then a family tree going back to at least 4 generations, get a copy of the property documents, then meet a good lawyer who is good/an expert in Hindu Succession Act 1956, Indian succession act 1925, Claims of Class I heirs, 2005 ruling for daughter share, then you can get a good answer to proceed.

The grand children have every right to enjoy the properties offered by the grand - father's provided the grand - father has made an will - a well documented paper signed by himself in a prescribed stamp -paper of the court.
The property owned by the grand - father can be distributed as per his will where the exclusion or inclusion - both may take place as per his desire.