I do not know if you have got any further with your enquiries of 7 years ago.I have just posted on this site for the first time.It seems to me possible that our searches are related. My grandfather, Michael Posner, also known on his burial cert. as Michaelis Posner was born in 1863 in the town of Altkloster in Germany. His father died in 1866, so we presume that uncles and aunts raised him. Could one of them have been your Pauline Posner?I know it is only speculative, but the dates are about right and they were all in Germany.