I've just gotten hold of the genealogical research of my great grandfather and can offer some insight.
General Alfred was the son of Stephen Pleasanton, grandson of Jonathon Pleasanton and Ruhama Lewis.
David Pleasanton, married to Deborah Luff, will probated April 5, 1774 lists 5 children: Nathaniel John David Caleb Sarah Wm Rodney, executor
Deborah married second Stephen Lewis, son of Daniel Lewis and Margaret Paradee.
Sarah married Outten Laws, son of Bolitha. His will lists 8 children: Alexander, Bolitha, Outten, Saxe Gotha, John, Deborah, Juliana and Amelia.The will lists Deborah as married to John Hickey of Philadelphia. Could Heverin be a second marriage?
Amusing note: 1753 will of John Pleasanton disinherits his son David "if my son David Pleasanton marries my wife's daughter Elizabeth Brinckle..."As if these families weren't already way too intermarried!
Would love to trade info with any interested parties