I looked for other postings you had written concerning this family and found a similar one written in Gilliam County, answered by "Laura":
If you have additional information on the family of Edna, please post it.Otherwise, I revisited the US Census and found some additional information that you may or may not have.
In the 1900 Census for Union, Grant County, Oregon
George D. Rose, born July 1866 in California to father born in England, mother in Kentucky, hotel keeper for zero months (newly employed), renting their home.
Edna G. wife, born August 1874 in California to both parents born in Missouri
Fa???ir Isaac P.Brother, born Oct 1872 in California to both parents born in Missouri
--the last name is written poorly, it could be F??gir.His relationship is clearly brother, the others are clearly Boarder's.So, it could be an enumerator mistake and he was a boarder.BUT, the born in California to both parents born in Missouri matches Edna.The name was transcribed as "Cleaac p. Farence"
The 1910 Census for Umpqua, Douglas County, Oregon
Geo. D. Rose, age 43, born in California to father in England, mother in Kentucky, farmer
Edna G, age 35, born in California to father in Missouri, mother in "Oaklahoma" (as spelled)
N.P. Cantwell, mother-in-law, age 57, widow, born in "Oaklahoma" to father born in Virginia, mother in Tennessee, mother of 3, 3 living.
Willie Cantwell, age 11, Lodger, born in Oregon to both parents born in Oregon.
--The questions arising in this census... If this "N.P. Cantwell" is the mother of Edna, Willie can't be her son as both his parents were born in Oregon.
The 1920 Census for Portland, Multnomah County
Geo D, 52, born in California to again both parents born in Kentucky
Edna G, age 46, again with both parents born in Missouri.
Also in Portland in 1920
Martha P. Cantwell, age ? (image is too light), born in Oklahoma to father born in Virginia, mother in Tennessee.
The Oregon Historical Records Index: http://genealogy.state.or.us/http://genealogy.state.or.us/
shows Martha P. Cantwell divorce from Dave Cantwell in 1908 in Gilliam County, OR.(She appeared to be the respondent)
--So, Gilliam county the place you idenified as the marriage of Edna, "appears" to be the county where her mother was divorced from Dave Cantwell.
This site also showed a "Delayed Birth" record for:
Ida B Cantwell, last name Knight, born in Morrow County 6/13/1883.
Wilma Edna Cantwell, last name Ramage in Gilliam County, born 10/11/1898
--The 1930 census shows her marriage to a Ramage, born in Oregon to father born in California, mother in Oregon.
Nancy Ethel Cantwell, last name Stewart in Clackamas Co, 3/3/1881.
--Oregon death records show she died 28 Nov 1977 in Clackamas Co, born March 1881.
I also found you had posted an inquiry on a Robert Cantwell, so, perhaps you do have information on the Cantwell family.Otherwise, I can't find any of them in the census.Martha P, may or may not be the mother of Edna Grace, but their is a connection, "probably" mother, but insufficient evidence.This Dave/David Cantwell can't be found either, so he "may" be the father of Edna Grace, or a later marriage by Martha.