I have managed to collect some more details of the family since my original post, and they coincide with yours except for a couple of details.
The first is I have Katie’s date of birth as 1894, not 1897; and the second, is that Alexander McKinnon’s wife is recorded as Cirsty McDonald on their marriage entry, however, in saying that, when checking for other records, I’ve also found her recorded as Christina. I wasn’t able to find detail of her parents or her death, so I can’t say for sure which one is correct.
I also have Alexander’s parents as Donald MacKinnon and Catherine MacDonald.
I was also able to track down the parents and grandparents of Elizabeth Young. Let me know if you require any of these details, either by the message board or directly.