I have some info about the George Job Elvey, he seems to have married for his 2nd wife Eleanora Grace Jarvis chr 7 jan 1819 St Martin Fields, London dau of Richard Jarvis and Ann perhaps Hayter. GF Watts did a portrait of Lady Elvey when she was still Miss Ellen Jarvis in 1837, later owned by their son Robert Victor Elvey. By his at least 3 wives he seems to have had several children. Your difficulty in researching this fr the antipodes stems fr the fact that he was the organist for St George's Chapel, windsor Castle and lived in Windsor, thus the normal records are not included in the IGI. I have a genealogical connection in London who has dug up quite a bit of information for me, although researching fr the Jarvis side.