Legal documents found in the Devon Record Office in 2006 by English family history researcher Anne Speight prove that Mary Tremlett and Peter de Vial were the parents of both Sophia Elizabeth de Vial and Mary Jane Vial. Mary Tremlett and Peter de Vial were married in Exeter in 1764. Mary made her will on 7 April 1776, leaving certain property settled on her at the time of her marriage to her infant daughters, Sophia and Mary Jane. Mary Tremlett died in 1776, shortly after making her will. Peter de Vial subsequently married Catherine Oak in 1782: she was the mother of Charlotte de Vial, Mary Jane's other known sister, as well as several other children.
An abstract of the documents has been requested from Devon Record Office. More information will be added to these pages when this is to hand.