Hi
I am just catching up with you, looking at the information I have it does seem that Isabella was born in Dunbar as I first thought, how she somehow managed to get herself from one side of Scotland to the other is a mystery although people were much more mobile that it is generally supposed.
The family seemed to have moved to Greenock sometime between 1831 and 1836 from that point on I have a complete record to the present day.
I suppose my next move will be to try to track down Blacks in Haddington/Dunbar.
You guys seem to be really on the ball and thank you for your efforts on my behalf.
Kind regards
Riversideresearcher