You have NEVER explained away the tombstone found in the Old Lewis Cemetery in 1948.
"General Robert Lewis" appears to be a patchwork of misinformation and myth. There was a Robert Lewis came to Virginia and settled in the Poropotank Creek area, but he wasn't any kind of "General" or any other officer, his wife was a widow with children from two previous marriages (her name is usually given as Mary), and by her he had only two daughters.
Another Robert Lewis, wife Elizabeth, emigrated to America on the "Blessing" in 1635 - but they went to Massachusetts, not Virginia.
As for the "Sir Edward Lewis of the Van and Lady Anne Sackville" part of the story, someone found a marriage record for them of October 7, 1622. His second and fourth sons both served in Parliament after the Restoration, William born c. 1625 and Richard born c. 1627. If there was a fifth son named Robert, he would have to be either somewhere between, or (more likely) younger even than Richard. There is zero chance he would have been old enough to emigrate to America in 1635, and very little chance before 1645. He would be in the same age bracket as the *sons* of John Lewis of Monmouthshire, and so cannot possibly have fathered any of them.