I think one thing which just might make things clearer would be if you could get the actual date of ANY of the deaths. You say that "a lot of her family were killed in the Warsaw ghetto during WW2.." Are you absolutely sure it was the ghetto, which would make pretty sure they were Jewish, which was destroyed in 1943, or was it in the Warsaw Uprising in 1944 when the Poles rose up against the Nazis in the belief they would be helped by the Allies, i.e. the Russians who were just over the river? The Russians sat on their hands for political reasons and let the Poles be slaughtered - I believe civilian casualities were about 30,000. If your relatives were killed in 1944 it would be fairly sure that they were not Jewish. Hope this helps a bit.