Hi Rose, Oregon State Archives has info about adoptions, see http://arcweb.sos.state.or.us/adoption.htmlhttp://arcweb.sos.state.or.us/adoption.html. However it looks like . . . well I'll let you read it and I won't speculate.
I did find info on the adoptive parents. Howard Allender filled out his World War I Draft Reg. card June 5, 1917. He was living in Lincoln Co., MT. He was b. Calais, ME, 21 Sep 1888. He was a laborer at planing mill, Libby Lumber Co., Libby, MT. He was single, no dependents but claimed an exemption from the War because of "weak eyes". He was med. height & build with blue eyes & light brown hair.
A Howard Monroe Allender married in Yamhill Co., 15 Feb 1919. Source: OR Marriage Index, 1906-1920.
Howard and Rosabelle were living in 1920 in Seaside, Clatsop Co., OR. Howard M., b. WI [that is what was written on the Census but mistake are made], 32, timber scaler govt forest; Rosabelle E., b. OR, 29, operator ____ ____.
In 1930 the family was living in Klamath Falls, Klamath Co., OR. Howard M., b. ME, 42, marr @ 31, electrician sawmill; Rosabelle E.., b. OR, 39, marr @ 28; Darleen J., adopted dau, b. OR, 7; Morris M., adopted son, b. OR, 3 and a roomer Harry E. Buck.
Howard M. Allender d. Multnomah Co. 25 March 1963 per death cert #4146 at age 75; spouse-Rosabel. Source: OR Death Index 1903-1998.
Rosabelle Allender whose last residence was Longview, Cowlitz Co., WA was b. 18 Sep 1890 and d. July 1972. Her social sec. # was assigned in OR. Source: Social Security Death Index which anyone can access at no charge. Her obit might have clues about other living family members.
A Morris M. Allender whose last residence was Longview was b. 5 July 1926 and d. 15 July 1998. His soc sec. # was assigned in OR before 1951. Source: SSDI.
A Darleen J. Allender was living in Salem in 1971. Source: Marion Co. Directory. Successful Hunting!