I should have said the those were the children of William and Mary nee Logue.
Susan Jarvis father William and mother Martha....can't get a match for Harley...I've tried a few different spellings. I think Martha may have been married before.
There is a Martha in the 1901 census with a child, Tillie
www.census.nationalarchives.ie/pages/1901/Londonderry/No__3_Urban/Fountain_Street/1529678The child is a granddaughter of the Campbells' so that must be Martha's maiden name...so I searched for Martha Campbell as Susan's mother and got a hit!
I also found a Kathleen May D b.1918 with parents William and Martha nee Campbell...twins??
You'll notice in the census that Martha's mother's name is Susan!
Martha was married to John Harley in 1897:
Martha and John had 2 other children:
Civil Birth Rebecca Adams Harley 1901 Co. Derry
Civil Birth Annie Harley 1911 Co. Derry
Familysearch has a record of the death of Rebecca 1902 and the death of Matilda in 1902.