I can find four Grace MOYLEs, born or baptised in Cornwall between 1769 and 1775. All four were born at Wendron. One died in infancy, one married (to Henry PRYOR) and I have no further records for the other two. Of course, there may have been other births or baptisms that I have not identified.
For a start, however, perhaps one of the other two Grace MOYLEs may be the one you are looking for. Here are their details:
Grace MOYLE, baptised at Wendron on 20 September 1772, daughter of Stephen MOYLE and his first wife,Dorothy MEDLEN, who were married at Helston on 11 November 1750. Grace was the tenth of their ten children.
Grace MOYLE, born about 1773 at Wendron, Cornwall, daughter of John MOYLE and Grace JENKYN who were married at Wendron on 2 February 1764, the fifth of seven children.
These two Grace MOYLEs were related, (the younger being I think half niece of the older) and both share with me as ancestors John MOYLE and Elizabeth JAMES, who were married at Wendron on 22June 1657 and who were my 7th great grandparents.
I would be happy to provide further information about this line of MOYLEs and would be interested to learn more about the descendants of your Grace in an effort to place her more firmly in our family tree.
There were several John, Stephen and Grace MOYLEs at this time around Wendron, and a couple of second marriages. There is therefore the possibility of some error in these relationships and if anyone has better information I hope they will correct me.