I found 3 Athertons listed in the Manning Cemetery.
This link will show you an aerial map and layout of the Manning Cemetery.
http://davidkusel.com/temp/cemetery2.jpg
Each section is marked A, B, etc and the rows described below start in the North East corner of that section going north to south and the next row going south to north.
You'll notice the Lutheran church just north of the cemetery and Center street just west of the cemetery.

Section B Row #36 South to North
Atherton, Frankie 1889-1891
Atherton, Halsey D. 1846-1919
Atherton, Ruth A. 1851-1917

I'll have to talk to Ging Hudson about the listing of the Atherton Family Stone which is listed in Row #35 North to South but has no names listed.

There are no other Athertons listed in the other Carroll county cemeteries.

I don't know if you found this web page I have but this link will show you the graduation years of Athertons.

http://davidkusel.com/manning1/MHS1888-1919.htm

1892, 1894, 1900 & 1901 are years listed for Athertons who gradutated in Manning.
I double checked the Centennial book to see if I made an error when I created the web page (since there are 2 Effie Athertons listed, one in 1894 and the other in 1900) but both years list an Effie Atherton in the Centennial book.

Hope this helps some.