The Poindexter book says John was b. 1720, the Flinn book has 1729-31.
The Flinns of Auld Ireland speculates that John was the son who remained in Lunenburg Co.
Lunenburg DB 2, p.480
In 1758, he was listed as a sergeant in the Virginia militia. Sunlight on the Southside, Vol. 1, p.193, states that John & James Flinn were colonial soldiers at least until 1774. There is one John Flinn listed as serving in the Revolution, but it's doubtful it was this man.
John was named, along with his brother Thomas, as executor of his father's will. Thomas relinquished. There were various suits against James in that capacity. Some likely in an attempt to recover debts of his father's estate.
Mecklenburg DB 4, p.330
Will of John Flinn, Halifax Co, WB 1, p.317
Another John Flinn was in Halifax but the age of the children as indicated in the above will is consistent with the age of Laughlin's sons. John, son of Laughlin, was a land owner. The other John Flinn apparently had no land, but he is said to have had two sons named William and John - he was still living in Halifax in 1785 with four whites in his household and by 1792, his wife, Elizabeth, appeared on the tax records. The son William perhaps married Sarah Wright on 24 Apr 1787 also in Halifax Co.
Sally Rion/Ryon is suggested as being Cherokee Indian, which I very much doubt. Neither do I know where the name Sally came from - she was obviously Rion, not Sally, in the above deed. In 1752, he is said to have bought land from John & Mary Thomson, on the N side of Bluestone Creek, close to Greenbrier, now in West Virginia. [This also seems doubful since his will is in Halifax.. His brother James had land on Bluestone Crk, located in Mecklenburg Co VA - it seems someone has confused the Blustone Creeks.] It is suggested he married about 1752. He was a Sergeant in the Virginia Militia from 1758 until at least 1774. His will probated in Halifax Co VA lists daughters Mary Rowland, Elizabeth Cox, and Sarah Stonewall, a son John, and a son William who was still a minor. Also an unmarried daughter, Nancy who married Elias White 1 Mar 1790 in Halifax Co. William may be the William Flinn who served in the Revolution and applied for his pension in 1833, District of Edgefield, SC. He stated his age as 73, or born 1760. so he would have been 19 at the time John Flynn wrote his will, indicating his son William was still a minor.