I would guess James Muir was born c1770, probably in Moonzie.
Elspeth Anderson/Muir would have been born around the same time in Moonzie.
Could you check for some of their children?
Robert Muir born 1794 in Colluthie, Moonzie.
Henry Muir born 1800 in Colluthie, Moonzie.
Catherine Muir born 1810 in Kilmany.
Any other children for James Muir and Elspeth Anderson would be most appreciated.
