Eliahu Pietruszka (102) discovered his brother Volf’s son, Alexandre, thanks to Yad Vashem. In 2005, Volf wrote a Yad Vashem page of testimony saying that Eliahu was dead. A cousin alerted Eliahu’s grandson which led to Eliahu meeting with Alexandre in Israel.
https://www.timesofisrael.com/102-year-old-holocaust-survivor-reunites-with-newly-discovered-nephew/