Moszek Icek Zylberberg, Joel Zylberberg’s son, was a wood trader who was married to Hudel-Cerla (Zvi Fisz’s daughter). They had three children, Sara Dvora (married to Yitschak Teitelbaum), Chana Bryndel, and Hershel/Hersz Joel.
Hershel was mentioned in the book Gone to Pitzipoli: A Boy's Desperate Fight for Survival in Wartime (Academic Studies Press, 2012) written by Rubin Katz:
We were allotted accommodation … with a family named Zylberberg… we had thought up an ingenious hiding-place in the form of an underground shelter dug beneath a small hen-house. The [Zylberbergs] also owned a timber yard on the Iłrzecka Street, across the road from us. They … were a well-respected Orthodox couple with a grown son and two daughters. … My family came up with the idea of building a concealed bunker below the hen-house, using it as camouflage, in partnership with the Zylberberg family. …Apart from my two eldest brothers, their son Hershel also assisted in the project. The work consisted mostly of digging and carrying away the excavated soil bit by bit. … About twelve people in all were crammed into the small shelter.
At the March 19, 1945 murders at the Krongold apartment, Hershel was severely wounded. In his book, Rubin Katz relates to the murder:
One of the injured was our old friend Hershel Zylberberg, who had helped build the hide-out in the ghetto below the hen-house. The Poles claimed to have come looking for a list of local Poles who had participated in the killing of Jews during the war, which they said the Jews had put together to perhaps inform the authorities. No doubt some had scores to settle, but there never was such a list; the demand was a pretext to come and rob the refugees, and the planned robbery ended in a killing spree.