The phonetic spelling of Dhu/Due/Dew was obviously recorded by different people at different times.

Similarly, Frances was spelt Francis at times, and Leita was also Letta and Lita.

...

The family name could have been Dew.

When brother Charles Dhu died, Henry and George Dhu mentioned in obituary:

https://trove.nla.gov.au/newspaper/article/25519235?searchTerm=%22c...

Death 1905/2140 Perth; Dhu, Charles, 59, son of Heffer DHU and Jane MORLEY

Death 1932/4900184 Goomalling; Dhu, Henry, 79, son of Heffer DHU and Jane MORLEY

After George Dhu (senior) died with that name, his wife and sons apparently used the Due name.

BDM WA

Marriage 1881/5171 Newcastle; Dhu, George, to Martin, Frances

Children registered to George Dhu/Due/Dew and Frances/Francis (Emily) Martin, at Toodyay:

1883 Dhu, Emily Jane, died 1884, aged 7 weeks.
1887 Dew, Lucy Louisa; Due m Hutchings; m Lofthouse; died 1924 aged 37
1888 Dew, George Simon, died 1888, 3 months old.
1889 Due, Hilda Rebecca; m Hyland, died 1907 aged 19.
1891 Dew, Percey. died Percy DUE 1937 aged 48.
1892 Dew, Emiley Frances; Emily Frances Martin died 1974 aged 81.
1893 Dew, Grace; Due m Trewren, died 1921, aged 26.
1895 Dew, George Frank, George Francis DUE died 1946 aged 54.
1899 Dew, Unnamed M, not born alive.
1900 Dew, Thomas, died 1900, 30 minutes old.

...

Death 1913/4900034 Deepdale, Northam; Dhu, George, 58, son of Unknown DHU

Born c1855

https://trove.nla.gov.au/newspaper/article/149562145?searchTerm=%22...