Hi, Well, I'm not sure that I can help you. Here is what I found. You most likely have all this.
John Lewis b: abt. 1729 Goochland, VA d: 1796 Goochland Mildred Lewis b: abt. 1737 Albemarle, VA d: 1768-1831 or 1769 in Spotsylvania, VA Some say that John remarried to a Sarah Iverson. If that it true then Mildred died in VA before 1796.
Children: Mary b: 1760 m: David Wood Meriwether Ann m: William Mosley Elizabeth m: Benjamin Halsall Nicholas b: 1765 d: 1812 m: Ann Meriwether Jane b: 1758 m: Zachary Meriwether Robert ? Charles ?
There are several Lewises and Meriwethers listed in some of my books but not sure if there is a connection. Nothing is popping out.
Have you tried to get a copy of a will and/or probate for John Lewis? Did he serve in Rev. war? If so, maybe one of the sons applied for a pension after 1820?
I would suggest writing to Goochland co. courthouse 9if that is truely where he died) and see if they have a will for him. If there is one it may list the names of beneficiaries. At least then you would know if Mildred was still alive in 1796. Be sure to include a SASE so they can respond easily.