Have only just discovered your post but I have the people you mention in my family tree which is posted on the Ancetry website. I have found William Garrod b. 1750's death on the BMD as Blofield Sept 1845 Vol 13 p. 13. From Freereg I have Francis's baptism at St Mary the virgin, Yelverton 27/10/1679. I can't find a marriage for John either but have William as his son.