Hi I am also a great granddaughter of William Mckinnon and Eliza Jane Murphy.
My Maiden name was McKinnon. My Brother, Father and Grandfather are all named William Malcolm Mckinnon. My Grandfather may be the missing child born 28/03/1897. I have his siblings as Lydia Elizabeth 1889, Annie Mckinnon 1891, Kate 1897, James 1899.
I know he was the son of Malcolm Mckinnon and think his mother was Elizabeth Young. Malcolms Parents may be Alexander Mckinnon and Christina McDonald.
Could you let me know how this compares with your findings?
Thank you for your help.