Martin Zieren from Germany recently contacted Nicolas Detering on my behalf regarding statistics of First World War poetry anthologies.
I have received the following reply from Nicolas Detering and would like to thank Nicolas and Martin for their help in finding more Germany female poets of the First World War.
From Nicolas Detering
"I have just finished a paper on Ina Seidel and Agnes Sapper, both of which are listed on your blog. The article will appear in a collected volume on Female War Poets from Germany, which is due to be published some time in early 2015.
Three female poets which you might want to add to your list are Ilse Frank (later Ise Gropius, see http://de.wikipedia.org/wiki/Ise_Gropius), Clara Blüthgen (http://de.wikipedia.org/wiki/Clara_Bl%C3%BCthgen), and Margarete Susman (http://de.wikipedia.org/wiki/Margarete_Susman), all of them wrote a number of war poems. Blüthgen published a moving poem called 'Vermisst' ('Lost') about the loss of her son Victor. Frank wrote a couple of poems about trench warfare from the perspectives of the soldiers.
Incidentally, the most successful German female war poets by far were Ina Seidel and Isolde Kurz, at least judging from the number of their poems in anthologies. "
I will be following up these leads and adding the poets to my ever growing list. I hope to report back to you shortly with details of the poets suggested by Nicolas, as well as details of the book he mentions.