Her great-great grandfather was John William O'Sullivan who passed in 1930, and was married 4 November 1896 Shortland, Thames, New Zealand to Susan Josephine Boyle (1868-1915).
That's where my information ends on the O'Sullivans...
I did find some information on their daughter Eileen (which I already have) here. It's odd that her husband's (James Kenneth Mc Lean's) grandfather is listed as Alexander B McNab (1837-1922) in NFS.
I have had most of my success in finding information on her New Zealand family through a collaboration with a very distant cousin found on geneaology.com, & then with the online births deaths marriages archives.
Here was some help on the Boyle line:
This is off of that line and I will have to come back to it since i stayed up til 5am inputting...whew...https://bdmhistoricalrecords.dia.govt.nz/Search/Search.aspx?Path=%2fqueryEntry.m%3ftype%3dbirths#SearchResults