I took a look at the 1880 census and it showsRobertborn Wisconsin and Augusta hard to tell, index says MI but image looks more like Wisconsin to me ?Edgar as born Michigan.
1885 MAY DAY, RILEY, KS
S.M., age 56, born VT
M.C.,a ge 51, born VT
A., age 9, born WI
R., age 7, born Wi
1895 KANSAS STATE CENSUS - OGDEN, RILEY CO.
S.M., age 65, born VT
Mary, age 51, born VT
Augusta, age 18,born KS
Have not found Robert after 1880, and not yet found marriage for Augusta
Here is Edgar in earlier census as you said you did nt have him as a child
1870 NAPLES, BUFFALO, WI
Samuel, age 41, born VT
Mary,a ge 36, born VT
Edgar, age 13, born MI
Emma, age 9, born WI
1860 NAPLES, BUFFALO, WI
S.M., age 32, farmer, born NY
Mary C., age 26, born NY
Eliza, age 11, born MA
Edgar, age 3, born MI
I found a possibility for Augusta but will have to try to find a marriage to confirm.
There is an Augusta L. Walter in Marysville, Marshall, Kansas in 1900
she is age 24, born Feb. 1876 Wisconsin
husband George Walter, age 38, born Germany
problem is I cannot find a marriage for them, nor can I find them in later years.