Hi Logcal,
Welcome to rootschat. I don't have a photograph of the headstone you speak of, sorry. That isn't to say that one doesn't exist, I only managed to take a few that day because of the very bright sunshine! (Never thought I'd tell anyone that about the Scottish weather).
The only information I can give is about the Scott - Graham stone and the Scott - Gibson one.
"Erected by James Scott late farmer in Moorhouse of Liberton in memory of Christian Graham his spouse who died January 1819 aged 72 years and 2 of their children interred here. Also the said James Scott who died 19th September 1839 aged 98 years".
"John Scott tenant in Libertoun died 13th March 1785 aged 75 years. His wife Susan Gibson died 6th May 1780 aged 74 years. Their grandson William Scott died 9th August 1783 aged 16 years".
Good luck with your research, sorry I couldn't be of any help.
Lodger