You could ask Auschwitz camp archives : http://auschwitz.org/en/museum/auschwitz-prisoners/
With this advice, available for Arolsen archives : these two institution display online only a part of their data.
As you are sure of internment of your aunt & uncle in camps, first Auschwitz, then probably one or more Diplaced Person camp (DP's), you must fill an inquiry form online on each website to get all what they possibly detain.
Archives & history of Medem Center - Arbeter Ring ( Bund / Workmen Circle) of France
Searching FLAM AGID around Lemberg
ZYSMAN KRONENBERG ROTTERSMAN arounf Lodz