I too have drawn in a blank when it comes to tracing people in India. In my case it was my gtx3 grandmother, Amelia Margaret Padam, an Indian girl who married my gtx3 grandfather, William Lacey, who was in the British Army. I know they married at a Church Mission Station in or near Benares on 05 January 1864. They had three children in India, including my gtx2 grandfather Christopher Lacey, but I've not found anything relating to a marriage certificate or a birth certificate for any of them, not even William Lacey's service papers. I've been to the British Library and the National Archives and got nowhere. It's really frustrating so you have my sympathy.