I think you will find a lot of the Harris family you are looking for on
www.irishgenealogy.ie just put in Harris on the surname search and look at the Kinsale entries. There are also some on
www.familysearch.org/records.
There is a birth record for a William Harris on 28 Dec 1877 parents William Harris & Catherine Lewis Sponsors John Harris and Johanna Browne.
On the 1901 census William ( Mary's father) is listed at his aunt's address of 33 Fisher Street Kinsale. William nephew age 23 Fish Merchant Hannah Browne head of house shopkeeper, and Julia Harris niece age 19 shopkeeper living in a 1st class house.
On the 1911 census William is 33 and his wife Bridget is 38 living with his mother and twins Mary & Richard living there. William and his mother listed as Publicans. I had a look for people with name Bridget in 1901 age 28 and there is only one in Kinsale a widow named O'Neill ( married name) and her father's name is Farsey - her place of birth is Co Clare. It is possible that this Bridget married William.
There is a marriage record for William Harris Kinsale Jan - Mar 1908 ref vol 5 page 164 might be worth getting this record from GRO (
www.gro.ie)
There is a birth record for a Wm Harris July - Sept 1916. ( might be worth considering if he was a brother to Mary and Richard).
There is a death record for Kinsale for William Harris (possibly the father) Apr - June 1921 est year of birth 1878 age 43 ref for GRO vol 5 ref 203.
Also there is a record for Susan Bridget Browne date of birth 27 Nov 1870 ( this could be William's sponsor on his baptism record and the aunt he was living with in 1901.)
It might not be right to assume that both parents were deceased for Mary to go into ophanage. Sometimes in those days, if perhaps a mother died in childbirth, the father was unable to look after the children himself and they were often sent to the nuns at the orphanage.
Hope this helps you and that I have jumped to too many conclusions!!
Mary