A few weeks after I posted this story, a generous findagrave.com volunteer named Kay Cynova traveled to Fridhem Lutheran Cemetery in Hordville, where I suspected the Wallins might be buried. (I had tried to contact the church with no success.) She found the graves of my great-grandparents, who were two of the charter members of that church—and nearby, in a second Wallin family plot, a small stone for Irene R. Wallin, 1921-1921. I feel quite certain this is the one, as my father remembered the name “Irene” being spoken in hushed tones by his aunts. At least now we have a name, and a proper memorial.