I'm told that you have to know the outfit (and all the numbers associated with it) to search for the individual.  My grandfather was in the Russian Army as a horse groom in that war but I've had no luck finding out anything.

Isabel Cymerman
Southbury, CT
Searching:  CUKIERMAN, CYMERMAN, DRONZNIK, GRYNFARB, SOLECZNIK, TABACZNIK.  Towns:  Przedbora, Siedlce, Warsaw