There are numerous user submitted ancestral files on familysearch.org - URL below - that indicate Elizabeth Beecher was the third wife of John Dunbar, son of Robert and Rose Dunbar of Hingham, MA. Might be worth looking at, to see if you can confirm the details.
User Submitted Genealogies at:
https://familysearch.org/search/tree/results#count=20&query=%2Bgivenname%3Ajohn~%20%2Bsurname%3Adunbar~%20%2Bbirth_place%3AUS~%20%2Bbirth_year%3A1650-1659~%20%2Bspouse_givenname%3Aelizabeth~%20%2Bspouse_surname%3Abeecher~
John Dunbar
parents: Robert Dunbar, Rose
spouses: Martha Aldrich; Abigail Norton; Elizabeth Beecher
birth: 1 Dec 1657 Hingham, Plymouth, Massachusetts, USA
christening: 13 Dec 1657 Hingham, Plymouth, Massachusetts, USA
marriage: 4 Jul 1679; Hingham, MA
ABT 1697;Plymouth, MA
24 Jul 1700 ,New Haven, , Connecticut
death: 1733 Hingham, Plymouth, Massachusetts, USA
burial: Old Cem, New Haven, Connecticut, USA
