hello James Wardlaw Crawford Miller was my great great grandfather. His son, Robert, my great grandfather was indeed a master mariner and became piolt of Kiama lighthouse in the early 1900s. He lived here with my grandmother Florence for quite a long time. Like you, I am also puzzled as to how the Miller surname came about. According to the marriage certificate you have, Captain James Wardlaw was his "reputed" father. I think that perhaps he may have been born out of wedlock to Jessie Crawford (hence the Wardlaw and Crawford names) and then perhaps Jessie married later on to a "Miller". Just a thought. So, if James WC Miller was your great grandfather we must be related. Nice to meet you :)