You cannot find births for James Alan MUMFORD and Raymond Leslie MUMFORD in Australia as they were born in England BEFORE the family came to Australia. Also they would have married/died AFTER the searchable years for QLD BDM...and may even still be living..
1944 Mumford Raymond L (mothers surname)Shepherd
1947 Mumford James A (mothers surname)Shepherd
plus other children you can search for at FreeBDM (just google)