First of all - Mairi - although I don't recognise the names straight off, William Grant and wife Isabella McBean are probably family somewhere. Drumullie is only about a mile from the family farm at Balnacruie. I'm hoping that for the moment this is a red herring, and I'll check into them later. Thanks for your interest.
Sarah - re the Anguses!!
Right - no 1, the Braemar one, I think we can rule out, as on the 1891, he is at home in Crathie with his parents Alexander and Anne and siblings.
No 2 - the policeman - much as I would love him to be mine (I was a police constable in the highlands myself in an earlier life!
), I'm fairly certain he's not mine. 
His marraige cert clearly shows his parents as Alexander Grant (a mason) and Margaret Collie. IGI shows him as their son, and confirms he has a brother Allan (with him in London on the 1891 you found). None of his childrens names are from my line at all. The Thomas and Ethel would work with his wife's parents names (Thomas and Elizabeth) - but where they've got Lewis and Mabel from is anyone's guess. Maybe Mabel could be for Margaret his mother, but Lewis??
Anyway, I think he's pretty much ruled out.
No 3 - the Kilmonavaig one. Again he's definitely out. Have him on the 1891 with parents Dugald and Jessie (Janet) and siblings. This is confirmed by marraige cert to Anne Kennedy 1893 and death cert 1948.
So looks like we are left with the Dores one and the North Morar one, but have to say neither look at all likely for mine as we have some parents details which don't match, as well as the wrong locations and years of birth.
So you're right - the Montana one has to be one of either of the above two - or mine!!!
I must give my dad a ring tomorrow. He told me ages ago that he had thought that his grandad or great grandad had gone out to America for about 10 years and then came back again. Now I have long since proved that this was not the case - but perhaps it was his great uncle, who would be Angus. Its possible that my dad would have known Angus when I think about it, as my dad was born 1930 and Angus could still have been alive then, about 66 yrs old. So if he lived to a decent age and came back to the home area, my dad could have known him as a boy. I'll have to try and jog dad's memory again.
I'll go try to trace the Dores and North Morar ones forward.
Cheers
Ellen.
![[talkingscot]](./images/smilies/talkingscot.png "[talkingscot]")