Uncle Bruce remembers a George Thomlinson, probably a half-brother of his father, coming to stay with them in the 1930s.
In the 1930 Census, there was a George and Myrtle Thomlinson, ages 11 and 12, listed as sister- and brother-in-law (respectively!) of W Drummond (?), head of household. His wife was Dora, probably James W's daughter and James Harrison's sister. They were in Jackson township, Daviess county, Missouri, where Mary Phillips, James W's ex-wife had come from.
In the Missouri Lookups
page, I found reference to a marriage between
Dwight Burns of Potosi, Washington Co., Mo. 25 years; Myrtle Thomlinson of Potosi, Washington Co., Mo. 20 years; Affidavit as to ages and qualifications; 22 April 1936 license; married on 23 April 1936 by Harry Brannaugh, JP at Potosi, Washington Co., Mo.
If Myrtle were really 20 in 1936, she would have been born c. 1916. If she were really 12 in 1930, she would have been born c. 1918. Might she have lied to avoid getting consent? It seems plausible that things were difficult in the Drummond household in the depths of the depression, and W Drummond and Dora might have refused her permission to marry.
The SSI death index doesn't show any matches at all for Myrtle Thomlinson, so she must not have been working for an SSI employer before she married (SSI didn't start issuing numbers until 1936). There are no high-probability matches for a Myrtle Burns with birth years in 1915-1919. Unfortunately, there are about a dozen possibilities, and at $27 each to check them out, I'll wait.