Hi i am trying to find a date of birth and death for 2 relatives.

The relatives i am searching for are : Patrick Hyland: born Ireland abt 1838 and his wife Margaret Johnston: born Ireland abt 1835-40
Margaret Johnston is my 3x great aunt.

All their family were raised in the Westchester area.

They had a son named James Hyland born New York 16 Dec 1858

He married a lady named Margaret no birth or death for her.
James and Margaret had 2 children:
Katherine ( or Kathryn) Agnes Hyland born 1888 died 1923.
John Vincent Hyland born 1880 died abt 1942

Katherine married a Ralph Benjamin Feriola. They had 3 children: Dorothy Ruth born 1915, Ralph jr born 1919 died 1935, Katherine Gloria born 1922
No marriage or children found for John Vincent

The blanks i would like to fill in on the family tree are: A date of birth and death for Patrick Hyland and Margaret Johnston. And a possible date of death for their son James.

I have come to the conclusion that either Margaret Johnston or Patrick Hyland may have died at an early age. I only know of the one son, James. And it seems odd they only had the one, considering most couples in those days had rather large families
I do hope someone can help. I am in the UK and it's not easy to just 'hop' on a plane to the local archives office :-)
Kind regards Janette