Change of Name

[GranvilleT]

This is my first post, so Hello to everyone,

I have only recently started my family tree and discovered my maternal Grand father is Australian so have started to look for Birth details on him but with no luck, the only information my mother has is that he was from Adelaide and named George Donald Roscoe born about 1904.  After much failed searching my Great Aunt (his sister-in-law) remebered he may have changed his name from Crowther.  The change of name came as a news to my mother who had always assumed that her father was call Roscoe.  I then found his marrage certificate and the name of his father Henry Oswald Roscoe.  Further research found a Henry Oswald Crowder listed in Births in Adelaide but no information on my Grand father. So my question is does anyone have any suggestions or advice for trying to find out further information on my Grandfather? 

Thanks in advance.