I think you may be misreading the pension document language. Kitty was the daughter of Wm and his 1st wife Martha Slaughter (not named in the pension document). Patsey, mentioned in the document was Martha Slaughter Broadus who did marry Merriwether Thompson -- the brother of William Mills Thompson who married Kitty.
You've probably noticed the Broadus/Broaddus issue. I use the single "D" since that's what my grandmother used.
As noted in my earlier message, my interest is in the Kitty and her Thompson line, specifically their daughter Martha Frances Thompson who married Samuel Campbell and lived in Loudoun County (Middleburg), VA.
If you have anything further on Wm Broaddus, etc., please let me know. I have more on both Kitty's and Patsey's lines.