How to add cast in my school leaving certificate?

I M Rajendra, leaving in Pune Maharashtra India. In my Fathers School leaving certifiacate the cast is mentioned. But unfortunetly in my school leaving certificate, there is only mentioned as a Hindu......But my original cast is Hindu-Sonar, Sonar is not mentioned. 

So, what is the procedure to add the cast im my leaving certificate? 

Please guide me.....my email ID is newaskarrajendra@gmail.com