How can I obtain a divergence certificate for name correction?

I wish to have my father's name corrected on my birth certificate. My father was baptized with one name but has used a common English translation for most of his documents. The MCGM Mumbai considers this a complete name change and has asked me to obtain either a court order or a divergence certificate. My query is about the procedure for obtaining a divergence certificate from the Department of Rural Development and Panchayat Raj or the Tehsildar's office, the documents required, and the fees if the process is done through a lawyer.