The one that's annoying me most is John McKenzie, who was born in Caputh 3 Jun 1855. The last definite record I have for him is 1881 when he and his sister Agnes are visiting their sister Jane Ballintine, where he gives his occupation as blacksmith.
In 1891 and 1901 there's a John McKenzie married to Catherine living in Renfrew with two sons, Robert and Allan. This John McKenzie is an iron worker, and gives his place of birth as Caputh, so I'm sure it's him.
The problem is I can't find a marriage certificate for a John McKenzie and Catherine god-only-knows, or a birth certificate for Allan or Robert OR a death certificate for any of the above!
Help. Going slightly bonkers.