Hello, probably it's not going to help but I checked the profile of Martha's husband Francis Grant. It says that he married twice with two women both named Martha Baker but one is born in 1729 in Barnstaple, Massachusetts (the one you are asking about) and the other (profile ID Baker-19653) in 1738 in Suffolk, Massachussetts. Her father was also different from the other Martha, named Preserved Baker. By this other woman Francis had a son named Henry. What if this is the real wife of Francis and also mother of his other children while the other Martha Baker was some relative of hers and married only Nathaniel Bingham?
Let me know if this can be a good theory.