mystery of Anna

My grandmother's name was not in the family bible when we searched for it during our 2013 visit to Finland.
We think that she was born around 1896.
She had three sons:
Martin born 1916
Paul born 1923 (my dad)
Henry born 1929
She wrote letters to Lydia - an older sister born 1885
She wrote letters to Kerttu - Lydia's daughter- probably born 1919
My grandmother's name was Anne
She came to Canada from Finland with my father when he was 5 years old to get married to a widower with 4 children.