Glad to see someone working on this line.What I have is info others have given me so please try to verify it....it's not the 'gospel'!But perhaps it will give you leads so you can do that very thing....verify it!
This isn't my line but I collect all info on the various spellings of the name.
David born 1808 was possibly the s/o James and Mary Cast Harvill/Harvell/Harvel/Harvil/Harwell.The following deed shows that James and David were known to each other. ("Genealogies of Virginia Families", publ. by Baltimore Publ. Co. as taken from "Tyler's Quarterly, Vol. IV (l923)", Volume IV reprinted in l98l, p. l80:[Dobson, Surry Co., N. C. - Deed Bk H:l49] (Abstract - sic) - Deed dtd 4 May l799. Isaac Elsberry of Surry Co. sells to JAMES HARVILL of CUMBERLAND Co., N. C. for $50.00, 200 acres on the great branch, beg. on a post Oak the corner of John Elsberry's former tract and running west 280 poles to a pine. Thence S. by a line of marked trees, an unknown number of poles, to the corner of the said Isaac Elsberry's own land whereon he lives, thence E. by a line to marked trees to the said Elsberry's S. E. corner, thence S. to the Old line, E. on a stake on the above named branch, thence N. l72 poles to the beginning - (signed) Isaac (X his mark) Elsberry -Wit: DAVID HARVILL, John Elsberry [the younger].Proved by the oath of DAVID HARVILL in Court at the May Term l799.BTW, the county seat of Surry is in Dobson, not far from Mt. Airy, N. C. (home of the famed "Mayberry" TV Series.)
Moses is thought to be the s/o David and Mary 'Patsy' Womack Harvill.She died in Surry Co. (Surry County, NC - Will Book 4:43(File 447A) May 14, 1832)They may have married in Johnson Co., NC or either Johnson, Wake Co., NC.I've seen it both ways.
This David is thought to be the s/o another Moses.
Three sons are attributed to this last Moses and one might have been born in Brunswick Co. VA and another in Wilkes County, North Carolina; so you see you have several counties to search if this family, indeed, lived all these places.
Now there is definitely a John Harwell who was married to Margaret Hill and he died in Cumberland Co., NC in 1766.His descendants spell their name Harville. We suspect he ties back to the Harwell family of Brunswick Co., VA through John H. Harwell the s/o Samuel Harwell and his wife, Anne Unknown.Soooooooo....it would be great to find documentation that connects your family to Sam & Anne Harwell who lived & died in Prince George County, Virginia but I haven't seen it yet.....maybe you are the one to do it!Or at least disprove it!
Hope this helps more than confuses you.Please remember this is not proven data as far as I'm concerned.Others may have more documentation than I in this line and if so, maybe they will either add to or correct!