Sorry for the delay. I have been on holiday. Thank you so very much for your response. I am very grateful!
I will search the websites you have provided.
Unfortunately I only have photocopies of the translations of the letters, not the originals or envelopes. No one seems to have the envelopes.
I had already begun to suspect that he had changed his name in Poland. He destroyed his Polish papers on receiving Australian citizenship. I am not sure how he would have obtained such convincing papers in Poland.
My Grandfather was practicing Russian Orthodox when he passed away.
I have filled out a form at Bad Arolsen and look forward to their response. Thank you again!