Just my thoughts & some more information
Elizabeth was Mary Ann (Corley) Hammond's daughter, probably illegitimate & step-daughter to Henry as she was born about 8 years before they married & Henry would have only been about 17 years old himself, not impossible though...
Then we have Harry/Henry Jnr born 1856 which also makes you wonder if there were any infant deaths from the date of their marriage in 1851 up until he was born?
Also Harry is Henry Eli one & the same person, probably dubbed Harry as his dad was already Henry, it is very common to use Harry for Henry.
As to the mother's name of Rebecca on Elizabeth's death registration, I'd say that possibly her sister Rebecca was the informant on her death certificate & filled it out incorrectly at the time.
Henry HAMMOND & Mary Ann CORLEY:Henry Hammond, son of
Henry Hammond and Elizabeth Dayley, born Jul 6, 1827 in Carbrooke, Norfolk, England and died Aug 6, 1911 in Bombala, NSW age 84.
Henry married
Mary Ann Corley, daughter of
James Corley and Sarah Edwards, July 18, 1851 in Caston, Norfolk, England.
Mary was born Oct 17, 1824 in Caston, Norfolk, England and died Nov 7, 1899 in Bombala, NSW age 75.
Henry immigrated to Australia with his Family on the ‘Lady MacDonald’ arriving October 12, 1856.
The passenger list shows the following:Henry – 27yrs – Norfolk - wheelwright – C of E - read & write
Mary Ann – 31yrs – Norfolk – wife – C of E – read & write
Elizabeth – 12yrs – Norfolk –
daughter – C of E – read & write
Harry- infant – Norfolk – son – C of E
Children: Elizabeth Hammond born Jul 3, 1844 in Caston, Norfolk, England, died Jul 30, 1928 in Bombala, NSW age 84.
Henry Eli Hammond born Jan 16, 1856 in Thetford, Norfolk, England, died Nov 18, 1921 in Gundagai, NSW age 65, buried in North Gundagai, NSW.
Another name for Henry was Harry.
Rebecca Ann Hammond born Nov 23, 1858 in Parramatta, NSW, died November 1, 1940 in North Sydney, NSW age 81.
Isaac Charles Hammond born May 2, 1860 in Parramatta, NSW, died June 18, 1934 in Parramatta, NSW at age 74.