Thanks for all of the above, still no Margaret birth cert/baptism to prove that Patrick and Mary are the parents although most likely, seems to be a gap between 1862 (Mary's birth) and 1881 when Mary gets married to Michael Smyth.
William Nugent and Teresa Buckley (nee Nugent) living in New St. on the 1911 census are the children of James Nugent and Catherine Delany, still probably related but not the roadblock beater.
With Margaret being recorded as being from Dublin in the two census, is there missing church records or records not online that could account for this, I know civilly not everyone was registered because it was a cost many families couldn't afford but in Catholic Ireland of the time Margaret wouldn't have gone un-baptised.