I have now completed piecing together the family of Leyson Hopkin Davy (1782-1872) and wife Elizabeth (nee Lawrence) (abt 1798-1837) in Southern Wales. Their children were Caroline (1822), Charles (1825), Edwin (1826), Elizabeth (1828), Henry (1831), Ellen (1832), Maria (1834), Catherine (1836) and Sarah (b. 1837, d. 1838). Mother Elizabeth died just after the birth of Sarah in 1837.
Leyson and 3 sons migrated to NZ and established farms in New Plymouth area. Sons married and remained there but Leyson returned to Wales. He died in Clifton (Bristol) in 1872, aged 90.
Much more detail if anyone requires.

Philip, I am unaware of any Jhnathon and Mary Davy or Vaughan.