In regards to your comments on the Laurens County Templetons, here is some data to add to yours and some which may be in conflict.
The SC archive records for the original plats for Robert, Agnes, Martha and James are dated in 1772. Since Agnes, Martha and James received 100 acres each, this means they were over 16 and not married when they arrived. Robert received 250 acres, which would be 100 acres for him and 50 acres for each of three additional family members. Those additional family members would have been his wife and two sons, Robert and John. The evidence that there was a senior Robert is based an 8 March 1794 appraisal for the estate of a Robert Templeton in Laurens County, which you may have. In other words, the family consisted of Robert Senior, his wife, Robert Junior, John, Angnes, Martha and James. Robert Junior and John would have been under 16. Robert Junior was born in 1762 and John in 1766. These two eventually left SC for Indiana.
A William Templeton arrived at the same time as the above Templetons and was granted 150 acres.
I have no record of a Thomas Templeton arriving in SC at the same time as the others.
As to David Templeton, I believe he was living in SC at the time the above Templetons arrived. I have found there was a David Templeton living in the York County, SC, area who received a grant for 300 acres on 30 Aug 1753, and he was still living there in 1765. He may have been the father of the David of Laurens County. Additionally, there was a James Templeton born in York County area around 1755, meaning his parents had to be living there. This James was awarded 90 acres on Bullock's Creek on 20 April 1771, and later that year purchased an additional 240 acres on the creek. This James later moved to Pike County, Missouri. James was born prior to 1755, meaning his father (if David) would have been born around 1730, or earlier.
I have documented this, and other data, in the "The South Carolina Magazine of Ancestral Research" (SCMAR)Volume XXXV, No.3, Summer 2007. My article is titled "Possible North Carolina/South Carolina Relationships."