Nathaniel Lovell Edgeworth was mentioned in his father's will.It is the youngest son that is refered to as "Yet unborn".Richard and Elizabeth named the sons with two names. The Lovell part in Richard Lovell Edgeworth came from Dick's great great grandfather Samuel Lovell.Two sons were named Lovell, the oldest and the youngest;ie, Nathaniel Lovell and Richard Lovell.Achilles Sneyd Edgeworth was the middle son, named after two stepmothers of Dick.
Nathaniel Lovell Edgeworth and Naomi Evans had 11 children.Anna Maria b. abt 1815 (Probably named for Elizabeth's mother and Dick's sister Maria Edgeworth).Then there was a Daughter born abt 1818 who probably died young.Richard Nathaniel was born Sept 5, 1821.Followed by Lovell, John, Matilda, Rachel, Sarah, Harriet, Augustine, and Herbert Ansley.
My line is throught John who married Martha A. Ogburn.Martha's sister Mariah married Lovell, John's brother.
Go to the Edgeworth web site for more info on the family.Search Google for Richard Lovell Edgeworth.Good luck in your search.