Hello Brendan,
I was reluctant to post this as the O'Connell's in my database were from Worcester, MA not NY. However they may be cousins and one married a Brosnan.
I have 3 children of William O'Connell/Mary Galvin from Castleisland(Millen or Mullin?) to Worcester, MA:
1. Dennis b. 16 JAN 1859 married Catherine Gearin (possibly in Castleisland) d. 17 NOV 1938 in Worcester, I have obit. and gravestone picture. Obit mentions sister Catherine O'Connell Brosnan
2. William b. 12 JUN 1861 married Margaret Coffey in Worcester, she died, he went back to Ireland in 1893. Second marriage in Castleisland to Bridget Crowley Daly(her second too) on 24 JUN 1899. I believe he stayed in Ireland
3. Catherine O'Connell b. circa 1870 Castleisland married Timothy Brosnan/Brosnihan 30 AUG 1894 in Worcester. She died 15 FEB 1953, I have her obit. Timothy Brosnan was from Castlisland b. 29 MAY 1864 to Patrick and Nora(nee Brosnan) Brosnan. He died 26 AUG 1940, I have obit. Timothy Brosnan was pallbearer for my gg grandfather Daniel Courtney in 1912. I have not figured out a Courtney connection yet. This Brosnan family had a large presence in Worcester, many of Timothy's siblings were in Worcester. Members of this Brosnan family have trees on ancestry.com
This is probably not your family but it may help another person with O'Connell connections.
Best regards,
Helen
