I erred saying William Niles of Monkton VT was born at Braintree, Ma. He was actually born 11 May 1756 at Lyme CT [Rev War pension application, parents not named, birth not recorded]. He married 20 Apr 1780 Abigail Hyde at Huntington, Fairfield Co, CT. He was counted there in the 1790 USC. By 1794 he moved to Charlotte, Chittenden Co., VT., and by about 1816 to nearby Monkton, Addison Co., VT. He died at Monkton 17 Apr 1848, age nearly 92. He was a justice of the peace, town selectman, and one of the organizers for the Baptist Church at Charlotte, and an inn keeper at Monkton.
Wm & Abigail's sons were: William Niles, Jr. [wife Melinda], Welcom D. Niles, and probably David. One of their daughters was probably Betsey the wife of Reuben Powell with whom she had marital difficulties. She may have resumed her maiden name later & lived with her father at Monkton). Another daughter may have married___Newell.
Wm Sr's birth wasn't recorded at Lyme, Ct. There were at least two Nileses at Lyme in 1756 who might have been thefather of Wm: Eliphalet (1721-1759) or his brother Ambrose  (1723-1793).
Wm Jr and wife Melinda are in the 1860 USC at NYC (he's shown as born CT, wife born NY, dau Melinda, age 28, born PA). He's deceased by 1870. Welcom D Niles is in the NYC (Manhatten City Directory, 1829-30).
David is mentioned in church records for 1809 when he reports to the church council a conversation his wife had with Reuben Powell concerning Reuben's wife Betsy. The recorded land records for Charlotte VT don't contain any deeds executed by David;however, his name and Wm's are mentioned in other deeds that do not appear to have been recorded in VT. There doesn't appear to be a record of David as a head of household in any of the VT or other state censuses.
The land records executed by Wm, Sr., include an interesting mention for Abial Niles. Land deed of 27 Jul 1820 by Wm, Sr., of Monkton mentions land bounded by Abial Niles at Charlotte. This may be the same Abial who married in 1804 at Croydon, NH, and was counted in the 1810 census at Marshfield, Washington (Caledonia in 1810) Co., VT, and was at Barton, Orleans Co., VT in 1817 where son Abial C. Niles was born. There's no mention of Abial at least before 1820 in the Charlotte land records. It's my guess that Abial may be a son of the George Niles (b1750 RI-d1821 intestate) of Franklin Co., VT., Danbury, NH, and Freetown, Mass.Abial was in Canada by 1822 but later returned to VT.
The quest for the parents of Wm Niles, Sr., and Abial continues.