Dear Molly,
Re the birth date of David Sunter he was born in 1762 and his wife Margaret Andrew born in 1764. I hope this helps.
One of their children Jean married a David Ritchie (my grandfather five generations back).
Do you know when she died ?
I have seen on Findmypast website that a Jean Sunter was buried on 5 August, 1849 in Kilconquhar, Earlsferry. It has that her husband was a David Dirkie. I am thinking maybe through poor handwriting David's surname was Ritchie.
Any views ?
regards
David