(unmarried); and her twin sister Baroness Natalie Hermine (Lilla) von Langen (1853 – after 1933), in 1888 married to the Samurai Yônojô Kashiwamura (Yo Kasiwa Mura), (Hagi 1849-Berlin 1912), ambassador of Japan and China, military attaché of Germany, Austria and the Netherlands at the Japanese Embassy in Berlin and glass manufacturer in Yokohama and Tokyo.
Their father was Baron Alfred Friedrich Franz Otto von Langen, Passee/Kirch Mulsow 1821–Moisall 1888, Troup Captain of the Dragoon Regiment of the Grand Duke of Mecklenburg and landowner of the districts Moisall and Moorhagen.
On 20 March 1896 Arthur Langen filed an official request at the Government Commissioner Robert Hue de Grais in Potsdam to have his name changed to 'Langen', which was granted to him.
Remaining sources produce the following, be it fragmentary, picture of his activities: Langen was the manager of Ludwig Barnay's Berliner Theater until the last moved to Wiesbaden in 1894.
In 1901 Langen traveled to London and obtained full copyright on the German editions of theater plays by Oscar Wilde.
Between 1912 and 1916 Langen worked for the Berlin branch of the Deutsche Verlags Anstalt (DVA), one of the major German publishing houses.
This branch flourished until 12 September 1917, when four major theater publishers merged into Die Vereinigte Bühnenvertriebe Drei Masken / Georg Müller / Erich Reiß / Kurt Wolff Verlag, Berlin.
From 1918 until his death in 1927 Langen traveled between Berlin and Solingen, where he worked together with, among others, Louise Dumont, the manager of the Schauspielhaus Düsseldorf and a close friend of his late mother.
When Grete inherited a considerable amount of money from her brother Georg after his death in November 1914, Langen also secured this estate for her.
As the closest relative in the area at the time of autopsy and identification at the Mortuary of the Institut für Rechtsmedizin of the Charité, he most likely determined Grete's burial place.