I too am trying to find out about Andrew Reive 1750 & Isabella Blake, but hitting a brick wall. I looked up 2 of their sons deaths on Scotlands People and it gives mother as Isabella Black. There is an earlier Andrew married an Isabella Black in 1728 at Eskdalemuir but that is too early for our Andrew, as his family were born 1792-1809. I have searched the graveyards around the Morton/Thornhill Dumfriesshire area as they seemed to have been living there about 1807 where daughter Isabella was born, but found nothing. Most of their children were born around Eskdalemuir. Do hope someone can solve this mystery.