The other Catherine Curtis marriage that peaked my interest was the in 1878 to John Matthews -
Registration Number 1259/1878
Groom's Family Name MATTHEWS
Groom's Given Name(s) JOHN
Bride's Family Name(s) CURTIS
Bride's Given Name(s) CATHERINE
District Sydney
Funeral notice for Catherine Matthews appears in the newspaper in 1929 -
https://trove.nla.gov.au/newspaper/article/16522061?searchTerm=matthewsSydney Morning Herald 6 Jan. 1929
MATTHEWS.-The Relatives and Friends of Mr. JOHN MATTHEWS are kindly Invited to attend
the Funeral of his late beloved WIFE, Catherine Elizabeth; to leave her late residence, 11 Mount-street,
Pyrmont, THIS TUESDAY, at 1 p.m., for Church of England Cemetery, Rookwood, via Mortuary Station.
NSW death index gives little info -
Name MATTHEWS CATHERINE E
Registration Number 63/1929
Father's Given Name(s) 78 YEARS SYDNEY
Mother's Given Name(s)
District SYDNEY
Find A Grave -
https://www.findagrave.com/memorial/189180116/catherine-matthewsI'm not certain what details would be in the 1878 marriage certificate? Some sources says details can be hit and miss in these 1860-1870s certificates? If it contained her birth place and parents then might be well on the way to solving Arthur John Hughes origins?