Based on the Hindu Succession (Amendment) Act, 2005 and key Supreme Court rulings, here's a clear explanation of your family's situation:
Key Legal Points 2005 Amendment to the Hindu Succession Act: This amendment gave daughters equal coparcenary rights in ancestral property, just like sons. It applies regardless of whether the father was alive on the date of the amendment (September 9, 2005).
This was clarified by the Supreme Court in Vineeta Sharma v. Rakesh Sharma (2020). Cut-off Date for Valid Transactions: If a partition or sale of ancestral property was completed before December 20, 2004, it is protected and cannot be challenged under the 2005 amendment.
However, oral partitions or unregistered documents are not automatically valid unless proven in court.
Your Case: Your grandfather died in 2018, well after the 2005 amendment. If the partition claimed by the opponents was not formalized through a registered deed or court decree before December 20, 2004, your mother and her sisters can still claim their rightful share.
The burden is on the opponents to prove that a valid and binding partition occurred before the cut-off date.
What You Can Do Check for documentation: Was there a registered partition deed or court decree before December 20, 2004? Challenge oral or informal partitions:
Courts often reject oral partitions unless there's strong evidence. Consult a property lawyer: A local advocate can help assess the strength of your case and represent you in court.