I think the name of the witness 1869 marriage is Margaret Curtis Tarrant?
Margaret is born in Cork, Ireland. Given that there are numerous Irish-born settlers in the colonies at the time, the birthplace might just be coincidence, but might lead somewhere.
NSW records immigrants 1855 Mangerton
TARRANT Richard 40, Alice 31, Alice 12, Richard 6,
TARRANT,Alice Curtis m. ORCHARD, William Briggs
TARRANT, Margaret m. OLIVE, William
ORCHARD, Alice Curtis 1933/C3944
parents Richard TARRANT/Alice Hester CURTIS
OLIVE, Margaret 1918/C3439
parents Richard TARRANT/Alice CURTISS
TARRANT, Richard 1860/C257 parents -/Esther SNELL
b. Ireland 60yrs
death TARRANT, Alice 1878/C1579
parents Thomas CURTIS/Margaret WINN
Morning Bulletin (Rockhampton) 2 mar 1889
murdered 15 Feb at Cooktown George Tarrant only brother of Mrs B Orchard and Mrs W Olive, 32yrs.
TARRANT christened Mallow Parish, Cork, Ireland
Margaret 22 FEB 1842 parents Richard Allice
Richard 13 MAY 1849 parents Richard Allice
Alice 29 AUG 1852 parents Richard Alice