At the moment I am ok that Daniel Secord of the Grand River, born 1756, in Westchester county New York, married to Elizabeth died 1832 in Brantford, Ontario, is the son of Peter Secord . I have no specific proof but it seems more likely that he is Peter's son. I don't have a name for Peter's first wife either but according to other descendants Peter Secord born 1726 in Westchester county, New York married 1]Abigail [Montross]? 2]Abigail Emmett 3] Rebekka Brown.
All the children belonged to the first wife, as David Secord is the only child by Abigail Emmett according to a descendant of David Secord.
Rebekka Brown was named in his will. Peter Secord was very old  when he died on Talbot road in the District of London Ontario.
There is a publication done by R.Robert Mutrie, a Mabie descendant who has a book called " Secord of Charlottesville twp , Norfolk county, Upper Canada" as well as a book on "Secord of Brant county,Upper Canda" "A Long Point Settlement Genealogy". These publications give details and proofs of these Secords.
I have talked to other Secord descendants about these publications and found them to be a good source.He has a website on the Norfolk Historical Society page and information on many of his publications.
Thanks for your response. Pat