All right then… Preston H. SMITH was son of David D. SMITH. Online records show Preston was executor (along with Aletha SMITH, apparently David’s wife) of David’s will, and there’s more according to “Names & Sketches of the Pioneer Settlers of Madison County, New York,” by William H. Tuttle:
#1. David D. Smith of Hamilton; wife Altha (?); daus Anna Louvinna, Lucy, Clarissa (?) Amanda; sons Preston, Nelson, Reuben. May 11, 1833.
@ pg 230: David D. Smith settled in Hamilton 1807. Lieut. in 65th Regiment 1816. Died April 3, 1833, aged 50. Buried at Hamilton Center. Wife Aletha Preston. Sons Preston b 1809, Nelson, Reuben, David, Jr.
Where David D. SMITH came from I don’t know. A query about him in 1998 drew no responses.
You notice there’s no mention in the quote above of Edwin F. SMITH. Apparently Preston and Edwin weren’t brothers; maybe Preston is not connected at all to Edwin. Nor is Edwin mentioned elsewhere in the quoted excerpts from Tuttle’s book.