Using Ancestry records this is what I see for Honora McGRATH, arriving "Corona", 1879, Sydney -
All New South Wales, Australia, Assisted Immigrant Passenger Lists, 1828-1896
https://www.ancestry.com.au/search/collections/1204/Name: MACGRATH Honora 20 years
Native Place: Limerick
Parents names, and , if alive, their residence: Limerick **** WILSON (might be Eliza)
Religious denomination: RC
Read Write: both
Relations in the Colony: none
Name: ENGLISH Johanna 20 years
Native Place: Limerick
Parents names, and , if alive, their residence: Michael & **** Limerick
Religious denomination: RC
Read Write: both
Relations in the Colony: John CONWAY cousin
New South Wales, Australia, Immigration Deposit Journals, 1853-1900
https://www.ancestry.com.au/search/collections/2000/Name of Depositor: John CONWAY
Deposit paid: 3 Dec 1878
Person for whom remittance is made:
Residence Name & address of referee
ENGLISH Johanna 19 years Ballinagrana Thomas FITZGERALD
McGRATH Honora 21 years Kaldronin
Ireland
At 1879 and arriving "Corona" Honora McGRATH has no relatives in the colony.
From the obituary for Patrick McGRATH, died 1932...he is 86 years old and arrived at age 23 years ......arrived ~ 1869.
New South Wales, Australia, Immigration Deposit Journals, 1853-1900
Apart from finding names on the NSW BDM index what documents do you have for BDM?