Confirmation deed from previous owner

The property in question is a residential plot in a small layout in Bangalore, it comes under gram panchayat and has E-Khata in the name of current owner. This property was acquired by Mr Muni in 1964 through GramPanchayat, Which was passed on to his son Sampangi. Mr Sampangi created a small layout in this land, after which one of his four sons filed a case against his father and 3 brothers for the share in the property. There is a court decree with details of site numbers awarded to all the brothers and his father. One of the sons of Sampangi, Mr Lokesh (has two sons) got site number 10 along with few other sites. Mr Lokesh then sold the Site number 10 to Gopal, now Mr Gopal is selling the same site number 10 to me. Our lawyer says I need to get confirmation deed from Lokesh that his two sons would not claim the property in future. However, Mr Gopal who is the current owner says there is no need for such confirmation deed, and says he does not want to approach Lokesh for the same. Is the confirmation deed from Mr Lokesh really necessary? Please help.