As full a transcription as possible of Susanna's will has been on my website for a while, credited to me although I was not the only one involved in deciphering the microfilm image. Yes, it mentions daughter Christian Abernathy. Also Daughter Jane Robinson and Grandaughter Mary Bethell. But it contains no clues whatever to specify who was the Father of each daughter, nor the order of Susanna's 3 sons (Thomas Parham, George Tillman, & John Tillman).
As for your Lucy/Lucretia, I stated who she was: Lucy, daughter of David Abernathy (born cir 1705/6 died 1783/4 Dinwiddie County VA) & his wife Ann Liles (for whom we have no dates at all); the only date we have for Lucy is her birth date, after which she evidently disappears from historical records. I am aware of no other extant document which even mentions her. There is no documentation whatsoever to indicate her Father's connection to any other Abernethy/Abernathy Family. None.
Instead there is the DNA results (with paper trails, some very solid, others less so) of some 25 direct line male descendants of: 1) Robert Abernethy of Charles City County VA (b cir 1632/3, d before Feb 1685) & wife Sarah Cubisha, 2) William Abernethy (b cir 1645, d. c 1717 CT) & wife Sarah Doolittle, 3) David Abernathy(b cir 1705/6 d 1783/4 Dinwiddie Co, VA) & wife Ann Liles, 4) Charles Abernathy (b cir 1720 d 1795 Brunswick County VA) & wife Alice Short, 5) James Abernethy (b cir 1730 VA d 1785 NC) & wife Elizabeth Cox, 6) Charles Bernethy (b cir 1775 PA d 1813 OH) & wife Elizabeth Unknown, 7) Thomas Abernethy (b 1 Mar 1775 d 9 Dec 1837) & wife Electra Smith, 7) Michael Abernathy (b 23 Nov 1803 NC d aft 1880) & wife Isabella West, plus 1 descendant of a probable out of marriage birth from sometime aroung the Civil War in AL or TN.
All of these individuals are very very close matches with one another and define what I call "the Scottish Group" of our Abernethy/Abernathy Y-DNA Surname Project, ongoing now since midsummer 2005. We also have what I call "the Irish Group" of 8 individuals and three who match no one else at present.
Here are some dates you can research that we know or believe apply to _this_ David Abernathy, of Dinwiddie County VA:
13 Oct 1727, purchase of 52 acres. 7 Aug 1761, purchase of 67 acres. 2 Aug 1755, Bristol Parish Survey. 5 Jan 1760, Bristol Parish Survey. 26 Jul 1763, Bristol Parish Survey. 31 Aug 1767, Bristol Parish Survey. 1782 Dinwiddie Tax records (land, 150 ac). 1784 Dinwiddie Tax records, David's estate. 1787-1792 Dinwiddie Tax records, David's estate.
The land grants came from the online files of the Library of Virginia's website and are sumarized along with many other land grants on my website, the tax records are available on microfilm, inter-library loan, and rather difficult to read (I was privy to the research by a noted and very meticulous historian for a number of Southern Virginia Counties where Abernathys settled, and I have full copies of all his notes sumarized on my website, http://bellsouthpwp.net/n/s/nss8660/DNA/DNA.html)http://bellsouthpwp.net/n/s/nss8660/DNA/DNA.html), while the Bristol Parish data all came from Churchill Gibson Chamberlayne's "The Vestry Book and Register of Bristol Parish, Virginia, 1720-1789", published by Heritage Books Inc, Bowie MD 20716, ISBN (softcover) ISBN 0-7884-0919-0.
Presently I am only interested in Abernethys, Abernathys, or any of that surname's myriad variations, and although I make note in my database of spouses, I tend to concentrate on what is applicable to the current project: direct male lines for DNA analysis.