Elizabeth, I have found another Frederick Briggs in Virginia that may be the one you are looking for. He would have been a cousin of the Frederick we discussed earlier who was the convicted horse thief and son of Robert Briggs. This Frederick, son of Thomas and Frances Briggs disappeared from Sussex Co VA after 1764. See below.
I found the information copied below in Southside Virginig Genealogies, a CD by John W. Pritchett, 2007, Genealogical Publishing Co. Inc.
Hope this is helpful.
Thomas Briggs, son of Samuel and Mary (Bailey) Briggs, and Frances were the parents of five children whose births are in the Albemarle Parish Register. At least one daughter was born before the start of the register. Thomas Briggs got a patent for 180 acres on both sides of the south fork of the Meherrin River in Brunswick (now Lunenburg) County and 300 acres on the north side of Couches Creek in 1741.In May 1749 he bought 112 acres on Hunting Quarter Swamp from Richard Avery.Thomas was a sergeant during the French and Indian War.
Frances Briggs died 2 September 1751,and Thomas married second Agnes Washington, the widow of Thomas Washington. In 1755 Thomas and his wife were residents of Surry County when they sold 511 acres on Hunting Quarter Swamp — possibly the land he inherited — to Ephraim Knight.Thomas bought 215 acres in Surry County in 1756.Thomas Briggs purchased 350 acres on Three Creeks 11 November 1755, which he and Agnes sold in 1762.That same year they sold his 215 acres in Surry County to Michael Nicholson.
In 1760 Thomas gave four slaves to Peter Jones who had married his daughter, Lucretia.In 1761 Thomas gave a slave each to daughters Sarah and Jane and in 1763 he gave “one Negro boy Roger” to his son Frederick.Three Sussex County citizens appraised the estate of Thomas Briggs in 1776,and his son-in-law Peter Jones reported on estate accounts of Thomas Briggs, deceased, in 1790.
Children of Thomas and Frances (—) Briggs 3› Lucretia Briggs [586.3.1] married Peter Jones.See their family 3› Joel Briggs [586.3.2] (28 Mar. 1741) was married to Ann by December 1784 when they deeded 50 acres in Brunswick County to David Roper. 3› Jane Briggs [586.3.3] (11 Feb. 1742/3). 3› Frederick Briggs [586.3.4] (14 Feb. 1744/5) disappeared from Sussex County after 1764. 3› Sarah Briggs [586.3.5] (18 Jan. 1747/8). 3› Rebecca Briggs [586.3.6] (7 Jan. 1749/50).