Hi Valerie - Wow, thank you so much for the information you've found! Are you related to the Duff family as well?
Here is what I've found on the Duffs via rootsireland.ie:
Baptism record 22-Apr 1849 for Christopher Duff, parents John Duff/Jane Dollard, Sponsors James Duff & Mary Anne Edwards
Baptism record 12 Feb 1843 for John Duff, parents John Duff/Jane Dollard, sponsors Joseph Boylan & Catharine Murray
Baptism record 21 Oct 1846 for Ann Duff, parents John Duff/Jane Dollard, sponsors Jackson Allen & Ann Walsh.
Marriage Record 12 Jan 1835 for John Duffe and Jane Dollard, witnesses Catherine Murray & Joseph Duffe. Parents names were not given.
Per Griffiths Valuation, many of the baptism sponsors appear to have been Chapel Street neighbors. Interesting that Catherine Murray appears more than once, perhaps she is family of some kind. Other than that, the only 2 Duff(e)s that I find among the Irish records I've located were James and Joseph.
My 2nd Great Grandfather, Christopher married Anna Breen here in the US. She was from the area of Cashel in Tipperary and her parents were Philip Breen & Dora Connell. Christopher and Anna had the following children:
John Joseph, Philip, Genevieve (aka Jane or Jennie), Dorothy, Alice, Richard. The first 4 children appear to have been named after their grandparents (John Duff, Philip Breen, Jane (Genevieve?) Dollard, Dora (Dorothy?) Connell). Anna Breen had a brother named Richard, not sure where Alice fits in - could that be after the Alicia you mention?
I've also just reached out to the Swords Historical Society to see if they could possibly help with researching this family. I've passed along the information I have and am waiting to hear back from them regarding their thoughts as to their ability to help. I'll post more once I hear back.
Thank you again for what you've done so far - I really appreciate the assistance!