I haven't found the parents of your Sadie. Places to search beyond Ancestry.com and Family Search include Minnesota Historical Society - state census, births, deaths - www.mnhs.org
, and Minnesota Official Marriage System www.mncounty.com
I did find a John Sanasec in Faribault County, Minnesota, born about 1872, found in the 1875 Minnesota State Census at www.mnhs.org
The Sarah J. Sanasac who married Clarence S. Cahill in 1906 in Waseca County, MN, is found on Find a Grave as SADIE, buried in Portland, OR. Born 1888 in Minnesota.
Her father is said to be Joseph Eli Sanasac born 15 Dec 1857 in Kankakee County, Illinois. Mother Marian Baxter (MARRIAGE of Joseph and Marian found on MOMS 13 March 1886 in Blue Earth County, Minnesota). Joseph had a wife before Marion, Josephine Markett died 1885. 1910 census in Waseca County, Minnesota gives five children in household of Joseph and Marion: Karrie, Florance, Ivan, Vernon, Stanley.
Point being Joseph could be related to "your" Senasacs and if so it might be worth looking for Sadie's father in Kankakee County, Illinois. Could be a wild goose chase - I suggest it only because we're not finding John and Frances in Minnesota.
Also note - some Senesacs seem to have lived in Canada and I suppose a John Senasac could have migrated to Minnesota long enough to have Sadie.