Agnes Provan Shanks had her passage to Canada in 1923 paid for by the Salvation Army, and she seemed to be going to work as a Domestic with them in Toronto.
...Isabella was 20 when she made her voyage in 1926, and she seemed to have with her someone named Jean Watt [aged 18]. They had both come from the same address: 14 St Vincent Place, Glasgow, which I think would be a place of work rather than their home address. ...Isabella had come from Airdrie,[as you know] and Jean Watt's home address was 13 Loanhead Cres, Newarthill. They were both going to "Govt Hotel, Toronto." Both were domestics.
I couldn't find a marriage for either Isabella or Agnes. Maybe someone would tell you the best site for looking up marriages in Canada after 1923.
About Agnes... I was wondering if she was only working for the Salvation Army or if she was actually a Salvation Army Officer. The Salvation Army keep good records in London for anyone who was an officer with them, and helped me to find someone on my own tree who was missing for many years. ....It turned out she had been with the Salvation Army for over 30 years!