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
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.