Edward Hampton had a son James, but it was by his first marriage to Dwens _____. James resided in the old Hampton Court Homestead at Lelant, while his father removed to St. Erth and married Eleanor Tresise, with whom he then had son Robert.
Please see my "Too Many Edward Hamptons?" post on the Hampton Board for clarification.
As for Elizabeth, who married John Trewhella, she was not the daughter of Edward. Edward left a will in 1654, in which he named only his son Robert, and 'the sons and daughters of my son James'.
Elizabeth was apparently the eldest daughter of Edward Hampton of Lelant (who was the eldest son of James Hampton). She predeceased her father, without any issue (her husband John Trewhella remarried to Catherine Hingston). John Trewhella was a witness to the 1692 will of Edward Hampton of Lelant, his former father-in-law.