Have you found the marriage of Deborah and John Carew for her maiden name? If that was Hann then there is a possibility of a link. Remember that the records we see are usually baptisms, if you are lucky to see the originals, some have the births as well but not all. There is a difference in the baptism years which is significant, if Mary Carew was adopted by the Hanns, I would expect a "rebaptism" if there is such a thing, after the Carewbaptism, not before.