There are very few resources available for Passamaquoddy genealogy in the 18th Century. Have you visited the reservation and spoken with the historian there? If they married in the Catholic Church there would be a record of her parents or prior husband (if she was a widow) in the church register.
The Ne-Do-Ba Research Journal 
sarah molley newell married francis miller native American history she was born 1740 pleasant point any in fo would be great
There are very few resources available for Passamaquoddy genealogy in the 18th Century. Have you visited the reservation and spoken with the historian there? If they married in the Catholic Church there would be a record of her parents or prior husband (if she was a widow) in the church register.