Unless the Jefferay document (excerpt appended) is spurious, it represents a convincing contemporary assertion that Frances Latham (etc.) was indeed married to "Lord Weston," written by a contemporary neighbor and kinsman who claims to have known her well. Your assertions to the contrary have the flavor of good research, however. Any suggestions as to a reconciliation?
Might Grandma Frances have embroidered her résumé?
Jefferay on Clarke and Latham
1652. I was chosen on a committee with three others to write a letter for Newport to Providence and Warwick.
This year here died Mr. Jeremiah Clarke. He hath left a good report, and a widow with many children she had by him. She is the faulconer Latham's daughter, he still living in Elstow, Old England, but now very aged.
She hath been twice married before, first to Lord Weston, and then to Mr. Dungan, by which last she had several children that came with her and her latest husband, Mr. Clarke, to Newport. One of her Dung-an children hath married Mr. Holden, of Warwick, and another is wife to Mr. Barker of this town.
Mrs. Clarke lately desired some discourse of me touching her husband's affairs, and showed me her father's portrait, which she brought with her from England (or hath had sent her since, I know not which). There be few portraits in this place, and this hath therefore a double value. It maketh one see an old man with long white beard, high nose, and piercing eyes, still clear and strong (perchance remaining so from their use in hawking). In the corner of the canvas is displayed the coat of arms of the Lathams, early a Lancashire family as I believe.
The Journal of William Jefferay, Gentleman…(1591-1675), being some account of divers people, places, and happenings, chiefly in New England, A DIARY THAT MIGHT HAVE BEEN, edited by John Osborne Austin, 1899, Press of E. L. Freeman & Sons, Providence, Rhode Island. Excerpted from The_Journal_of_William_Jeffera.jpg, downloaded 9/2/2012 from https://play.google.com/store/books/details/John_Osborne_Austin_The_journal_of_William_Jeffera?id=xpO8wuoOVFAC#?t=W251bGwsMSwxLDUwMSwiYm9vay14cE84d3VvT1ZGQUMiXQ..