Hi John
Had another go trying to find Finlay and he's still hiding
In respect of Margaret, I think she is certainly, from the censuses and DC verification, a sister to your Finlay. Why her mother has been indexed as Margaret Gray, I have no idea other than probably you would have to see an original extract from the OPR to see whether there has not been an error. She is living with William in 1841:
Margret Glass 45, b. R & C
William Glass 45, agri. lab., b. R & C
Elizabeth Gilanders 12, b. R & C
Address: Upper Kinkell, Urquhart, R & C
As you say, she is still with William in 1851 at Kinkell before dying in 1859:
Margaret Glass 61, sister
William Glass 56, head, tanner of 8 acres
Janet McLennan 14
After this William went to live with (or they came to him) Finlay and Ann in Kinkell, where they show together in 1861.
From the info you posted, Ann Gray/McKenzie's DC, and confirmation that she was a widow by 1886, I tried to find her in 1881 and no joy. I have (after battling with the wildcards) found Ann, by now a widow, and brother in law William living together in 1871.......under surname GLAP (
- or scream!).
So, all I can say now is that Finlay died between 1861 and 1871.
I'm not sure how much you have on the other lines. I'll post separately for clarity.
Monica