Looks like we may be related! My father was born in a small village called Sklene in Czechoslovakia in 1939. (He moved to Canada after the war and is unsure of its exact location. He thinks it may be in present-day Slovakia.)
His mother's maiden name was Marie Koretz, and she was born in 1919 or 1920 (I have to look it up!). Her parents were Anna and Michael Koretz. She had younger two siblings, Margaret and Leopold. Leo died at the age of ten -- but if it is a recurring family name, perhaps we are related since you know of the Leo Koretz in the States.
My great-grandfather (Michael's father) was called Joseph (Josef?)Koretz.
I have no birth dates and no solid birth years on Anna, Michael, and Joseph, but I have their Canadian death records. Here is the info I have. If the birth years ring a bell, please email me:
Joseph Koretz: Died 1957/12/28 Age:91. Born approx. 1866 Anna Koretz (Koretz is her married name): Died 1982/6/27 Age:86. Born approx. 1896 Michael Koratz (changed spelling of his ln upon arrival to Canada): Died 1954/10/31 Age: 63. Born approx. 1891