RE: Giles Briggs I have two items which help identify Giles with Jonathan.One is Jonathan's will (Dec. 1837) which mentions his son "Jiles" (I received a copy from Donna Wachtel); the other is from a biographical encyclopedia of families in New London County, CT:
"Jonathan Briggs and his wife were the parents of the following children: Giles, born in Coventry, went to Medina County, OH, where he died, leaving several children..." Genealogical and Biographical Record of New London County Connecticut; J.H. Beers & Co. 1905.
I have looked for Giles in the ancestry.com census images and found him in Concord, Niagara, NY in 1820; Sardinia, Erie, NY in 1830; Brunswick, Medina, OH 1840-1860; and Medina, Medina, OH in 1870.
According to the "New London ... " book, Jonathan had two brothers, Henry and Anderson.The Henry you mention may be this brother.I haven't found any independent records on Henry, though I have found records for Anderson.