Welcome to RootsChat.
Have you got their father's name from the marriage?
Did they all stay in Ireland?
Have you got any of them on a Census?
How do you know Kathleen had two sisters?
What was their religious denomination?
Lots of questions but every detail gives people an idea where to search.
I don't have their parents info
Mary is on the 1901 Census of Ireland listed as sister in law to George Holmes and Kate Holmes (nee Pillsworth), Irish Church,born in England, no idea where.
Elizabeth is also on the 1901 Census listed as a servant along with her sister Kates sister in law Louisa Holmes, Elizabeth was Church of Ireland born in Curragh Camp.
George and Kate and their 3 children moved to Chatham between 1910 and 1917, where they apparently got married again in March 1917, original marriage in Ireland in 1899.(No idea why there is a second marriage,perhaps they didn't have their original certificate and needed one for some reason).
there is a listing of marriage of an Elizabeth Pillsworth in the Irish Civil Register in Dublin South in 1903 but no spouse is listed, vol 2 page 483, GS film 101260,Digital folder 004199362,Image 00287.
They had cousins with the surname of Rock, and there is a listing of a child Charles Rock mothers name Pillsworth,no Christian name listed, it shows event date 1942 but registration 1903??
Hope this helps you, look forward to hearing from you.
Thanks
The info was obtained from a distant cousin who has the info on her family tree.