Eileen: My G G granddather, Denis Ryan (born < 1800, d<1852) lived in Cormackstown - just down the road from Farneybridge. {His agnomen was "Barney" meaning his father or grandfather was a "Barney" or "Bernard"). [Family history says he had brothers: Barney, Thomas, and Denis.] He was married to Mary Gleason. His sons were: Bernard (b~1800-1820); James Xavier Ryan (Barney) (b~1822, d-1878) - my great grandfather; Timothy b~1830; and Michael b-?. I have no information about any daughters of Denis.
Given Irish naming patterns; and the same (albeit commoon) given names of Denis, James, and Michael; it is quite possible that my Denis was a grandfather, father, or uncle, of your Denis (born 1815). My Ryans, emmigrated to Newport, KY and/or St. Louis, MO during the famine. My father had aunts & uncles named: Dennis, Elizabeth, John, Johanna, Margaret, Michael, and Joseph. Finally, there was a related branch of my Ryan family in St. Louis headed by James and Margaret Ryan (both born about 1844), although their exact relationship to my great grandfather is not known.
If any of this sounds familiar, let's chat: IrishStew