If someone was living in poverty in Glasgow in the 1920's, they would most likely be living in a tenement.
....I am not so sure about whether or not it would be a tenement in Bellshill though, and I can see that this would make a big difference to your story.
Try a google for "Old Photos of Bellshill, 1920's" and see if anything comes up.
There is a census for 1911, and a Nellie Gentles aged 5 is living at Bothwell district, which would take in Bellshill. .......John Gentles, her father is a Blacksmith at a Colliery, and his wife is Maggie. There are EIGHT children in the house, including Nellie. And it says that John Gentles & Maggie have been married 25 years, have had eleven children, of which 10 are still living.
Perhaps there were others put into care...? The address Nellie appears to be living at in 1911 is Ashley Gr....? [difficult to read it].
P.S. There is a site which is local to the area called The Lanarkshire Family History Society.
P.P.S. The address of the Salvation Army Headquarters in London is: The Salvation Army International Heritage Centre, House 14 William Booth College, Champion Park, London SE5 8BQ. ...If you are trying to contact them by email, then the google to use to explore their site is: House 14 William Booth College, London.