The Capt Matthew Fuller who lived in Barnstable left a will and his daughter Elizabeth was still married to a Mr. Rowley at that time.I don't think the Elizabeth Fuller that was married to Thomas Upson can be the same one.Our family records show her as divoced but two other records I bumped into have her listed as a widow when she re-marries.
Unfortunately, just about every 17th Century family had a daughter named Elizabeth so it's rather hard to place her. Her birthdate is a little soft and there are records showing her being born in Hartford and christened in Fairsted, Essex, England on the same day.
Of the Fullers I'm aware of are Samuel Fuller, physician (Mayflower), his nephew Samuel Fuller (child of Edward Fuller - Mayflower), Susannah White Fuller - widowed the first winter and married John Winslow (Mayflower), Robert Fuller (Salem 1639) - probably a relatively close cousin of the above Fullers.
I haven't found a Fuller family in Hartford other than Elizabeth though others may have.