It's a long time since your post, but perhaps you will pick this up!
I believe Katherine (or Catherine) was my grandmother's younger sister. My aunt Ethel always said her own aunt had gone the the USA.
My grandmother was Anastasia Healy and was born on 5 June 1874 in Kinsale, daughter of James Healy & Mary (nee Donovan). She moved to London, England and married my grandfather, Arthur Edward Durtnall, in 1898.
Catherine was born 26 March 1879. There were 10 children altogether - the others were Mary, Bridget, Honora, James (died), Margaret, James, Kate and Teresa. Anastasia was number 7 and Catherine number 8.
Their father James was a seaman and they lived in Friar Street, Kinsale.