William Lacy of Green briar County

I've seen a post somewhere on this genforum in response to John Lacy and Sarah Porter stating that he was born in 1761 in Rockingham County North Carolina and that he was there until 1764. Since Iknow that his father is William Iwas wondering what documents shows that William of Greenbriar County or any William of that matter was in Rockingham County NorthCarolina. Iwas needing to know this because Iknow that my Philemon Lacy was a member of Matrimoney Creek Baptist Church in Sept 1776 and Philemon has been said to be a possible son of William of Greenbriar. If William was there then this lends more Credence to the Claim. Ido know Philemon was in Pittsylvania County Virginia in 1771 which isn't to far from Rockingham County and then in Rockingham County in 1776 and he was listed in the Washington County Tenn tax list in 1778 with one white poll. Also the same year of 1778 he is supposed to be in Yohogania County Virginia on a Petition but is this the same Philemon.
Any help apreciated
Darren Altom