https://shackfordgenealogy.weebly.com/shackford-blog/wedding-wednes...
This blog has that Abigail Shackford, the first wife of Captain Samuel Shackford, is the daughter of Mary Richards The blog writers claim "we've reviewed the summary of Abigail's mother's [Mary Richards] probate records which mention that administration of her estate was granted to her son Samuel Richards and his brother-in-law Samuel Shackford of Portsmouth on Feb 10, 1702/1703."
Since there are no children attached to Mary Richards and her husband, William, I cannot tell if this is the correct family.
