Mary's surname was not Andrews. That was the surname of Thomas's second wife, whose first name was,coincidentally, Mary. The maiden name of Mary the witch remains undocumented, in spite of various claims.
The alleged Bigod ancestry of this Barnes/Scoville line is apocryphal, probably fabricated deliberately by some charlatan genealogist many decades ago and unfortunately widely repeated to this day on the Internet. There is, however, a legitimate royal ancestry through Selah Scoville, great-grandson of John the immigrant. Selah's 4G-grandmother was Agnes Harris, a documented royal descendant.