Hi Sue,
John may know more, but I am aware of three Alexander headstones and one McAlexander, but no McClellands.
Here lyeth the body of Janet Logan wife to Alexander McAlexander who died May 12th 1758 aged 42 & 2 of their children. [With coat of arms and motto, Quod Tibi Ne Alteri.]
Erected by MARTHA ALEXANDER in memory of her beloved husband CONWAY McNEICE of Cogry who died 21 November 1863 aged 70 years. [With coat of arms.]
Erected to the memory of JOHN ALEXANDER of Cogry who departed this life in the year of our lord 1815 aged 67 years. [Beside the one above, capitalisation of letters all over the place.]
Erected [by?] [J]AMES ALEXANDER [Carnlea?].
Gilby