http://mdhervey.com/xtra_pages/archive/HERVEY/HBOOK.PDF Page 9 shows her parents
Will have to look for Thayer records for children.
I don’t see any issues about Mary (Thayer) Burt.
"New England Historic Genealogical Society." New England Historic Genealogical Society. N.p., n.d. Web. 24 Jan. 2014.. Notes marriage "Thayer, Mary and James Burt, Sept. 2, 1685.*" Mary and James Burt, Sept. 2, 1685. Intention not recorded. Ancestry.com Source: Vital Records of Taunton also in Torrey’s New England Marriages before 1700 AncestryImage
There was a different Abigail Harvey - married to Briggs of Braintree I think.
The Harvey book : giving the genealogies of certain branches of the American families of Harvey, Nesbitt, Dixon, and Jameson....says that Abigail's children, other than Nathaniel, were not known. The other issue I am wondering about has to do with Abigail's husband. There are records that show there were two Nathaniel's, born the same year (probably cousins) about a month apart. If you look at Nathaniel Thayer's profile, someone added the notes about the different Nathanials and that the birth dates were different. No one has changed the dates yet in the profile though.