It appears that Mary and George were living together as a couple before they were married. The marriage registration I linked to above indicates that both gave their residence as being in Moose Jaw, Saskatchewan. I found a Fred and Mary Ann Gilbert on the 1911 census in Saskatoon. They have Mary Ann's daughter listed as Jennie Gilbert and two other daughters named Daisy Irene and Gwendoline. Here's a link to the census image:
http://data2.collectionscanada.gc.ca/1911/pdf/e002105000.pdf Some of the information is a little out but the Saskatchewan Vital Statistics genealogy database does have a birth for Daisy Irene Gilbert on 3 Oct 1908 to Fred Gilbert and Mary Ann Baker. There is also a death for Daisy Gilbert on 23 Jan 1916 in the database.
On the 1916 census for Manitoba, Saskatchewan and Alberta, the family is in Saskatoon as follows:
Fredrick Gilbert, 32, born England, immigration year 1906, teamster
Mary Ann Gilbert, 30, born England, immigration year 1906
Jennie Gilbert, 11, born England, immigration year 1906
Winnie Gilbert, 6, born Saskatchewan
George Gilbert, 4, born Saskatchewan
Again the information is a little out regarding Jennie.
The LDS Family Search site has a death for Gwendolyn Steele, daughter of Frederick Gilbert and Mary Ann Baker at this link:
https://familysearch.org/pal:/MM9.1.1/FLK5-W7WUnfortunately there is no image available.
Here is a link to Gwendolyn's marriage registration:
http://www.rootschat.com/links/0u0a/I believe this is the death for son, George with Mary's surname misspelled as Grodcott:
http://www.rootschat.com/links/0u0b/So far I can't find anything on Stephen or the other three children (Joseph, Christina and Lillian).
Jacquie