Do i need to get the singature of heirs in sale deed?

No need to get Owners signature, but you have to look in to the GPA Copy executed by the owner in favour of Builder/ developer wherein the OWNER has given his consent or power to transfer/ sell to the builder.

Consult a local Lawyer of your area to get know wether the builder has taken all the approval, plan saction, NOc and other things from the concern authority... and his power under the GPAor Development Agreement etc,.

Thanks Shyam. I saw the GPA where the owner gave power to sell his property. I will check with the other things like plan sanction, etc

why will the owener give GPA to the builder ... consult a lawyer to see how authentic the document is .... try to include the orignal owener as much s you can to avoid further claims or disputes. please do not forget to collect the chain of agreement and do a property search by the agency to see whome does the property belong 

consult an advocate

Mr Anur tripathi, when a builder comes up with Jiont Development Agreement with the owner he requires some power/ right over the proeprty that right will come to the builder through Development Agreement in order to implement or make it enforce he gets GPA to sell his part of proeprty like 40: 60 Ratio...... like this owner gave the GPA

To clarify, I checked the documents. The owner has executed a joint development agreement with the builder and appointed builder as his power agent to sell the property on his behalf