Legal rights on property distributed by parents

Your co brother has a share in said land and house. 

How did your grandfather allocate the property to both sons by a gift deed/partition/oral?

You have stated that the property allocated is ancestral, so it has to devolve upon all the legal heirs of your father.

However, the facts posted as well as query is not clear, it is advisable to seek professional guidance of a local prudent lawyer.

Hi Mr. Reddy, If your grandfather’s property was formally partitioned between his two sons and that partition was legally documented, the property would have become self-acquired in the hands of each son. In such cases, the legal heirs of each son would inherit only their respective shares. If your co-brother is claiming a share now, decades after the partition, and especially after you have listed the property for sale, his claim may not hold legal merit unless he can prove that the partition was not executed properly or was fraudulent. However, if the partition was not documented or if the property remained undivided, it may still be considered ancestral, and all legal heirs could have a claim. It’s essential to review the property documents and consult with a legal expert to assess the validity of his claim.   

For further assistance on this matter, please feel free to contact me at adv.vishesh@icloud.com.

Not at all. This was shocking for us as he has his share from his fathers side. 

What do you mean by co-brother? Do you mean your father brother's son?

Has the grandfather's property been partitioned by metes and bounds among the sons?