A couple of weeks ago I spotted on the Hamburg Cemtery details on CWGC that it was one of four where burials had been concentrated from other cemeteries in Germany
The four are
Berlin South Western
None seem to be particularly in the South but the last refers to Russian burials.
The cemetery was begun by the Germans in 1915 for the burial of prisoners of war who died at the local camp. During the war almost 3,000 Allied soldiers and civilians, including French, Russian
and Commonwealth, were buried there In 1922-23 it was decided that the graves of Commonwealth servicemen who had died all over Germany should be brought together into four permanent cemeteries. Niederzwehren was one of those chosen and in the following four years, more than 1,500 graves were brought into the cemetery from 190 burial grounds in Baden, Bavaria, Hanover, Hesse and Saxony. There are now 1,796 First World War servicemen buried or commemorated in the Commonwealth plot at Niederzwehren. This total includes special memorials to 13 casualties buried in other cemeteries in Germany whose graves could not be found. The following cemeteries are among those from which graves were brought to Niederzwehren: BAYREUTH TOWN CEMETERY, Bavaria. 24 burials of 1918. DARMSTADT FOREST CEMETERY, Hesse. In use from 1915. 102 burials. DIETKIRCHEN PRISONERS OF WAR CEMETERY, Hesse-Nassau. 45 burials (28 of Irish regiments) of 1914-18. FREIBURG IN BREISGAU MAIN CEMETERY, Baden, 43 burials of 1918. GERMERSHEIM CEMETERY, Palatinate. 26 burials of 1915-1918. GIESSEN MILITARY CEMETERY, Hesse. 99 burials of 1914-1919. GOTTINGEN MILITARY CEMETERY, Hanover. 88 burials of 1914-1919. HAMELN PRISONERS OF WAR CEMETERY, Hanover. 70 burials of 1915-1918. INGOLSTADT CEMETERY, Bavaria. 23 burials of 1917-1918. LANGENSALZA PRISONERS OF WAR CEMETERIES No. 1 and No. 2, Prussian Saxony. 225 burials of 1915-1918. MAINZ MILITARY CEMETERY, Rhein-Hessen. 23 burials of 1915-1919. MANNHEIM MAIN CEMETERY, Baden. 21 burials of 1916-1918. MESCHEDE PRISONERS OF WAR CEMETERY, Westphalia. 49 burials of 1917-1918. OHRDRUF PRISONERS OF WAR CEMETERY, Thuringia. 107 burials of 1915-1918. PADERBORN CEMETERY, Westphalia. 29 soldiers burials of 1914-18. QUEDLINBURG CENTRAL CEMETERY, Prussian Saxony. 102 burials of 1914-1918. SENNELAGER PRISONERS OF WAR CEMETERY, Westphalia. 32 burials of 1914-1918.http://www.cwgc.org/...ry=91502&mode=1
You may want to check the locations of the 'feeder' cemeteries plus some of those in the other three.