In the 1880 Federal Census, F. M. Remington & Irene are living in Silver Creek Precinct, Silverton, Marion Co., OR, with their two young daughters.
In 1900 they are at Spalding, Nez Perce Co., ID.
I am wondering if Francis Marion was "California" in the 1850 Census. That year, there is listed an older brother named Francis, born c1831. Perhaps that brother subsequently died, and the youngest brother's name was changed to Francis.