23 June 2022
Dear Dan
Not sure if this is of any interest to you but here goes. My husband, Richard (aka Rachi) Gross's mother was Rachel Casper. Her mother was Channa (various spellings of this) Margoliot/Margolis/Margolius. Channa's parents were Batya Cohn and Tanchum Abraham Margolius. We have a copy of a photo of Tanchum which he sent to Channa from Ponnevis/Ponevys with a message in Hebrew to her on her birthday. We've calculated that this was her 25th birthday. She was in South Africa then. Her husband was Joseph Casper. The original of this photo is with Rachi's cousin in Buffalo, NY. She had it translated in Israel. 
I'd love to know whether our Tanchum is connected in any way to your Margolis line.
Best regards, Beulah Gross (Australia)