Hello Brian
Francis Christie was born in 1799, dying on May 4 1872. He was married to Euphemia Brand, his father was Thomas Christy, I have the address of his death as Strachan Place, (I think it was Dundee)as I said, David did not know his grandmother's name.
Francis is of an age with my ancestor David and his brothers,
I'm not sure if his father Thomas was a brother to William and to John. There are a few Thomas's around who could be their father, but I stopped presuming anything re people's names, as they did not follow the usual pattern of naming children. My ancestor David and his wife Mary's first child, born after one month of marriage, was called Joseph, the Grandparents being William and Jean. No daughters were called Jean.
I did see a list somewhere on the internet re the professions of people living in Benholm, unfortunately William my ancestor is variously a farmer, roadman and general labourer. It is more useful if they were a miller, or had some sort of profession.
Have you looked up the Angus History Society? I've looked at it a few times to see if anyone else was researching the same names. (They weren't).
It occurred to me earlier, too, that you might want to check on Andrew's name being spelt Muir, or even Moore, I have many relatives having their names mispelt as Price (Bryce), Milne, (Mill) Kingcorn (Kinghorn) Mackay (McKay) etc.
Someone also advised if they owned any land, to look at the land registary records.
There may be a Duncan family history society, I have looked at a few Christie ones, but they seem to be mainly for Americans and the name was common around the Mearns. I joined the Kemlo Users group which has now ceased, due to the moderator passing away, there were people there who had info on every Kemlo living, unfortunately my own relative Jean, again must have come from a poor family with no record of her birth or marriage.
I hope this info might be of some use.
PS, You should try researching Great Grandparents, named John and Ann Smith!