Bearing in mind the information that McDonnell & McDonald are interchangeable maybe another clue.
I have a copy of a death record for a Margaret Andrews (widow) died March 1938 aged 86 years in Oamaru, NZ, shown as Married to a Richard Andrews. Margaret's father shown as William McDonald (Farmer), Mother listed as Margaret McDonald. Birth place shown as Cork, Ireland. Religion Roman Catholic. Number of years in NZ 66 which would put immigration 1871-73 period and DOB 1851-53 period
I had dismissed or felt this record as being for the incorrect Margaret due to the number of inconsistencies i.e. Birth Place, Age information inconsistency across records, Issue (Children) Living & age inconsistencies, Surname.
If date /age information is correct it would have had Margaret at 20 years or so when she immigrated to NZ! I not sure if it was common for young ladies of that age to be unaccompanied / single in that period undertaking such an adventure?