I can find nothing which indicates that Martha Elizabeth Kerr mother is a 'Morgan' ... and probably NOT the Morgans of Connecticut Colony.
None of the documentation on the children of John Morgan identify an Elizabeth with anything near this 1685 birth date (which is what *is* identified as Mordicai Rice's wife's birth year).
I propose cutting her from John Morgan & Rachel Deming/Dymond, leaving her as unknown parentage.