The birth index has Dorothy's mother as May PHIPPS. Possibly a transcription error as I see she married in 1901 as Mary Jane PHIPPS...
and death with some inaccurate information....
OSBORNE Mary Jane
Father George Summers Phipps Mother Annie Hutchinson ELLIOTT
At South Melbourne 57 years 1934 Reg#4930
Her parents marriage -
PHIPPS George born Kyneton
ELLIOTT Johanna born Ballarat
1878 Reg# 2362
and two deaths - possibly Johanna's husband and father in law. Johanna married Arthur HUTCHINSON in 1883.
PHIPPS George Sommers
Father George Sommers Mother Mary Ann BURNS
27 years Birthplace unknown 1880 Reg#4649
PHIPPS George Somers
Father George Somers Mother not recorded
65 years at Trentham 1888 Reg#12275
There are three births registered to George [Somers] PHIPPS and Mary Ann BURNS.
Frances Catherine 1859 Kyneton, Alice 1862 Kyneton and Selina 1864 Trentham.
From whom do you think your gggrandmother has gained her Maori ancestry? If it is her birth father, then you may have difficulty tracing him as he is not named on the birth index.
Cando