Upton Sinclair’s Hidden Network: Did Adelaide M. Branch (aka Mary Douglas) Work as His Uncredited Researcher for Decades?

I’m tracing the life of Adelaide M. Branch, the woman central to Upton Sinclair’s “The Heart Wife” account (Chapter XXVII) in The Brass Check (1919), which details Branch’s experiences in Monticello, NY, in late 1913, her conflict with local authorities, and the national press’s sensationalized coverage of her case.

Newly discovered evidence confirms that she later lived as Mary Douglas (see her 1948 NYC death certificate and census records, and international travel documents from 1919). Census records confirm that Mary Douglas was employed in 1920 and in 1940 (she hasn't been located in 1930), working as an independent writer or editor, but her published work has proven elusive. I am searching for evidence that might document her career or publications.

This part is interesting: Douglas’s 1942 case file with the Jarvie Commonweal Service (where she applied for financial aid) lists three references -- Dr. Edward H. Zabriskie of Newark, Gertrude O. Tubby of Montclair, NJ, and Prof. Walter Rautenstrauch at Columbia University -- all radical activists with direct ties to Sinclair (who first came to her aid in the 1913 "Heart Wife" woman he described in The Brass Check).

Lilly Library’s holdings prove Sinclair corresponded with at least all three references:

• Gertrude O. Tubby: Psychic researcher, praised Sinclair's "Mental Radio", and exchanged complementary copies of their books with each other).
• Dr. Edward H. Zabriskie: President of Dana College from 1920 to 1941. Prior to entering academics, Zabriskie was senior pastor (minister) of the First Congregational Church of Newark, New Jersey from 1918 to 1920.
• Prof. Walter Rautenstrauch: Cooperative movement leader (colleague of James Warbasse, another Sinclair ally who is known to have provided care and support to Adelaide Branch following her).

**Post-**Brass Check Silence: After 1919, Branch vanishes from records -- except as Mary Douglas, tied to Sinclair’s correspondents. Did she ghostwrite, research, or edit for him under the radar?