Further research found: -
I have found details on Louisa Pope (Eliza & John Richard's sister).
Eliza Pope married Robert Neil on 12 Dec 1850 in the parish of St James, Sydney, Australia. The witnesses were George Davis of Crown Street & Louisa Johns of Bathurst Street.
Louisa Johns was Eliza's sister. Along with her husband Frederick and daughters Frances & Laura, she traveled to Australia with Eliza on the "Petrel". Immigration records (21 Nov 1849) show Louisa's parents as William and Maria Pope (mother living in Bristol), with a brother living in Melbourne.
The Johns family are found in the 1841 England Census:-
Frederick Johns, 23
Louisa Johns, 20
Louisa Maria Johns, 7 weeks
All born Gloucestershire, England
Residing at Meadow St, St Paul Bristol
Ref: HO107/374/38/17
Karen