Not a 5th-great grandparent, Thomas Jeffress was merely a 4th-great grandparent and this is his will.  The will was proven in Lunenburg County, Virginia, on 12 August 1822. Again, I obtained this copy from the Library of Virginia's microfilm, Lunenburg County Will Book 8 pages 241-242.  He mentions his "beloved wife" but does name indicate her name.

The will mentions children Lucretia, Jennings, Polly, James, Eliza, Nancy, Lucinda, and Jane, in that order.  Because he further mentions that Jennings and Lucretia will inherit land from their grandfather, I assume that they had a different mother than the other children.  At least one SAR application paper lists Jennings's mother as a Ms. Motley, which makes sense because his middle name was Motley.

Thomas Jeffress's son Jennings Motley Jeffress married Susan D. Finch, whose daughter Susan Emma Jeffress married James W. Love, whose daughter Mamie Elizabeth Love married John Graham Barnett Sr, whose son John Graham Barnett Jr married Gracie Allen Van Pelt, whose daughter Jean is my Mom.

Thomas Jeffress's other son James Jeffress married Nancy Moseley, their son Edwatd A. Jeffress married Sally E., and their son William Arthur Jeffress married fanny Dorsey Price, and their daughter Sarah Burton Jeffress married my Uncle Jim Alexander. I believe this is the case, but I haven't proven it beyond a doubt!

So Mom & Sarah were descended from half-brothers, but they were both 3rd-great-granddaughters of Thomas Jeffress.