I'm no historian so this part of the family tree is speculative because records this far back give less information than their more modern counterparts.
Anyway, I believe Alexander Watson's (b.1823) father to be:
Henry Watson b.1792 in Boyndie (that's Whitehills in new money)
who was married to:
Margaret Priest b.1795 in Fordyce
and Henry Watson's parents to be:
John and Jannet Watson (as in her maiden name was Watson too)
Margaret Priest's parents:
William Priest and Margaret Wood
I do hope to read up on older records or get some help from the family history society in Aberdeen to clear up whether I'm right and could carry on tracing the Watson line.