Unsure of name and date of birth. At time of her mother’s death in 1885, their was only one female child living. Brian of nzolivers cannot find either female below died, so will be one of these two entries from NZ BDM website searched in April 2019:

1878/2673. Young, Margaret Jane. Mother: Bella. Father: John.
Born 4 February 1878

1880/3583. Young, Isabella. Mother: Bella. Father: John
Born 23 February 1880

However, looking at the New Zealand Electoral Roll it is clear that Isabella is the correct daughter of John Young:

New Zealand Electoral Roll - Napier Roll 1911, found in April 2019:
Young, Isabella, Colin Street, Port Ahuriri, spinster [Would have been aged 33]
Young, John, Colin Street, nightwatchman [Father]
Young, Annie, Colin Street, married [Father’s second wife]

New Zealand Electoral Roll - Napier General Roll 1914, found in April 2019:
Young, Isabella, Colin Street, Port Ahuriri, spinster
Young, John, Colin Street, nightwatchman [Father]
Young, Annie, Colin Street, Port Ahuriri, married [Father’s second wife]
Young, Annie, Colin Street, spinster [Step-sister]