Hello Tjtree,
Here is whom i think is your family on the 1861. census, in Glasgow.
William Marshall, Head, M. age 57 years, M. Shoemaker, born Ireland,
Mary Marshall, Wife, M. age 55 years, F. born Ireland,
Sarah Marshall, Daug, Un. age 20 years, F. Cotton Factory Worker, born Ireland,
Ann Marshall, Daug, Un. age 15 years, F. Cotton Factory Worker. born Ireland,
Margaret Marshall, age 5 years, born Lanark, Glasgow.
Address 109 Bridgegate Street, Clyde, Glasgow.
Now here is the interesting part, the young Margaret Marshall, aged 5 years on this census, was born 4/February/1856. Clyde, Glasgow, to parents William Marshall, Shoemaker Journeyman, and a Mary Cartmall, the address 80 Bridgegate Street, Clyde, Glasgow.
The only problem i see is the age of Mary Cartmall/Cartmill, is 55 years on the census, meaning she was about 50 years of age at the birth of young Margaret.
The father William Marshall, registered young Margaret's, birth he made his mark with a x. donating he could not write.
Regards,
Jonn.
Ps. the family were most certainly in the Clyde District Glasgow, as the first five birth of Ann Marshall, and Robert Stevenson, were in the Clyde District Glasgow, so also was Ann Marshall's, daughter Sarah Marshall's, birth also in Clyde District, before she and Robert Stevenson, got together.