Edward and Mary (Donaghoe) Lacy, and son Peter

My original immigrant ancestors, Edward and Mary, buried their son, Peter, with a gravestone that lists his origins.  It can be seen on Find A Grave, Memorial Number 92063254  The engraving is:  Peter Lacy The Parish of Arlas, Queens County Ireland.  Born May 9, 1844 or could be 1841.  In Irish Baptismal Records on Roots Ireland, Peter was baptized on May 15, 1842.  From US records and from written and spoken material of Edward and Mary's grandson, "Peter's parents are Edward Lacy b 1797, Ireland - died, 1885 Kentucky, USA and Mother is Mary Donaghoe b. 1815 Ireland - died 1887 Kentucky, USA."  Mary and Edward had additonal children born in Ireland and also in the US.  It would be great to learn more about Edward and Mary and perhaps communicate with relatives. Thanks for any help, Pat