1870 census Minneapolis: Horatio & Rosalia Follensbee with children Frank & Warren plus Mary Koloski (age 14, b. Canada). 1880 census Minneapolis: Horatio & Rosalia Follensbee with children Warren, Lulu A. & Louisa A. 1885 state census Minneapolis: Warren, Lulu & Louise living with Josiah & Rosalia Martin & some Martin children-looks like a 2nd marriage for Rosalia. 1900 census Clackamas OR: Louise, stepdaughter, living with Josiah Martin. 1920 census Clackamas OR: Louise H. Follensbee, sister, & Warren N. Follensbee, brother, living together.
Horatio was son of Moses & Jane (Alexander) Follansbee, and Moses was son of Moses & Sarah (Clark) Follansbee. The line back from there is pretty well documented. I think Horatio was born Canada: at least the 1870 and 1880 census says so. I suspect Mary Koloski was sister to Rosalia.