A report on the Sobibor transports by the Commissie tot het doen van Aangifte van Overlijden van Vermisten, the commission the Dutch government set up to trace missing wartime residents, indicates1 Charlotte Helene Grünebaum was a survivor of the March 2, 1943 transport from Westerbork, adding that she escaped from the train. The Westerbork transport registry2 and Grünebaum's Joodsche Raad card3 appear to confirm that she was deported with this transport.
If true, this would make her the only survivor of a transport widely thought to have had none.4 (Aside from the handful of exceptions mentioned in the Commission's list,1 none of whom survived the war, the whole transport is assumed to have been gassed within hours of arriving at Sobibor).
Grünebaum, like many escapees, was apparently recaptured and deported again - this time to Auschwitz,5 which she also survived. Grünebaum returned to the Netherlands, married a man called Walkate, and later in life helped establish a monument to The Hague's deported Sinti and Roma.6
Sources:
1. Stukken betreffende de transporten van Westerbork naar Sobibor van 2 maart - 20 juli 1943, 2.09.34.01 Inventaris van het archief van de Commissie tot het doen van Aangifte van Overlijden van Vermisten. (Netherlands National Archives)
2. Westerbork Deportation Registry (ITS Arolsen)
3. Joodsche Raad card for Charlotte Helene Grünebaum (ITS Arolsen)
4. Yad Vashem's entry for this transport currently states, "There are no survivors from this Transport."
6. Den Haag, Sinti en Roma monument (Netwerk Oorlogsbronnen); Roma- en Sinti-monument, (Wikipedia NL)