Ron -- Thank you so much for checking all of the sources you mentioned. I have some responses:

The 1930 Census for Portland, Multnomah County. Enumerated April 8. Otto L. Rustemeyer, age 37 (1892/1893), born in Washington to both parents born in Germany, logger-Bucker/Paper Company, age at first marriage 31.
Wanda, age 31 (1898/1899), born in Washington to both parents born in Poland, age at first marriage 26.

Otto was actually born in April 1891, so he would have been age 33 when he and Wanda married in 1924.

Dorothy, daughter, age 6 (1923/1924), born in Washington
--IF this is the correct one, Wanda was born in 1898/1899 in WA.

I haven't figured Dorothy out. I doubt that her maiden name was Rustemeyer. Most likely she was a niece of Wanda.

The Oregon Death Index shows Wanda K. Rustemeyer, death on 15 Sep 1942, in . . .
--an Otto "Lud" (database is truncated) Rustemeyer died 19 April 1976 in Multnomah, spouse Ethel, age at death 85, born April 1891. Ethel is shown buried at Willamette Nat'l Cemetery, for service as a Corporal, US Army.

Ethel was Otto's last wife.

--The World War I Draft Registration Card image database shows Otto Ludwig Rustmeyer, born 1 April 1891 in Uniontown, Washington. He was a logger in Chapman, Oregon. He was medium in heigh, medium in build, gray eyes and red hair. He claimed a physical disability.

The Washington Birth Index:
Francis Victor Neuhard, born 24 March 1916 in Seattle, to Francis Victor Neuhard and Wanda Dow.

I was told years ago that Wanda's first husband was Victor Nuehardt; and by him she had a son and daughter. The reference above must be for her son. He and his father had the same name, Sr. and Jr. I did not have Jr.'s date and place of birth. I found a little info on Sr., living in Seattle before his marriage to Wanda. I also found Sr. and Jr., living together and with no others in the 1920 Census, in Washington State. Jr. was age 4, Sr. was divorced. No Wanda to be found.

--I also looked for ANY Dow, born plus/minus 5 years of 1900 born in Washington. The 1910 Census had a Jenny Dow, born in Illinois, with daughters Lowienne, 13, born in Washington; and sister Clara, age 28 born in New York. Lowienne to Wanda? They were found in Seattle.

This is a good find. I still think Wanda was born in 1897, with her son born in 1916. Wanda being born in 1899, would have her marriage to Vic Neuhardt in 1915, with her only age 16. Maybe she was that young.

Does ANY of the above match with what you may know? Any additional information might help. The leads are just to limited. I even checked British Columbia archives info.

I don't know of any connection to B.C. Otto Rustemeyer was born in Eastern Washington, moved to Idaho at age 6, and settled in Portland, OR for his entire adult life. I found Otto and Wanda in the Polk directories in Portland for 1937, 1938, and 1941/42. In the first 2 the listing was just for Otto and Wanda. In the latter directory, it was them plus a single woman listed as Irene N. Rustemeyer. I vaguely recall being told that Wanda's dau. was named Irene. Most likely the N. was for Neuhardt, and she just used Rustemeyer as her surname, since that was her mother's married name.

Is it possible to search in Portland public school records for Dorothy Rustemeyer, born about 1924, and for Irene Rustemeyer, born, say 1917-1920?