The origins of Tilmon Niblett have, so far, not been traced. The existence of Edmund Niblett born around 1793 and Andrew Telghman Niblett born around 1804, both in Georgia, is evidence that a family existed probably in South Carolina in the mid 1700's. The use of the name Tilmon (Telghman, Tillmon, Tilman, Tillman and MacTillman) has been used subsequently in the family.The one family known to have been in South Carolina was that of John Niblett and Jesse Mock and his origins were likely to have been in Surrey, Virginia.
If you will write to me at my e-mail address I will send you the record I have of the Niblett family in the USA and maybe we can compare notes. As a point of interest I have seen the gravestones of Tillman Valentine Niblett and his wife at the Ellis family cemetery at Monticello, Georgia. I have yet to link this Tillman with the rest of the family although I know he was born to James E Niblett and Frances Daniel on Apr 15, 1850.
The Neblett side of the family (name changed from Niblett around 1740) has been extremely well documented by Dorothy Neblett Perkins in her book "Some Nebletts in America" but the Nibletts being one branch that retained the original spelling are not so well recorded.