Jeronimas was married with three children. It is known that Jeronimas, already married, went to the United States of America. While he was away, the couple drifted apart and divorced, but Jeronimas continued to raise and care for all three of his children. On his return from the USA, he settled in the village of Sviliai, where he probably owned a mill. In the village of Sviliai he met Adele Grigaityte, a midwife, who was 18 years younger, and married her in 1936. This was also Adele's second marriage, and she had an 18-year-old son Zenonas. The children of Adele and Jeronimas got on well with each other, and the spouses themselves also warmly welcomed each other's children.

In 1944, the family was approached by an old acquaintance, Chaja Gell, who asked them to help - to save her family and the families of several other relatives. The Žiužniai agreed to help, and one night Jeronimas and Zenon drove to Kaunas (about 60 kilometres from their village) in a wagon, and waited at the ghetto fence until Chaja's cousin Chaja Gell and her two children Rachel and Jacob came through the hole in the ghetto fence. Zenonas and Jeronimas brought the Jews to their house and hid them in a hut where they kept food. A few days later, Chasia's husband, Israel Gell, and several other Jews joined the hiding. In total, 14 people were hiding with the Žiužnys, two of whom were children at the time. Among those in hiding was an architect who invented a place for everyone to live under the kiln. They used to sneak in through the fireplace. Through the iron bars of the kiln - they would take them off and everyone would crawl in. Inside, they made bunks and ventilation, so that you could somehow manage to be. The Žiužnys helped these people for 9 months. Zenonas used to take a horse with a so-called "bricka" and bring a lamb, a piglet or a calf, Jeronimas would go to the forest to hunt, and Adele took care of food, hygiene of the hidden people, and all the other needs.

After the war, the people who were rescued left a written thank-you note to the Žiužnis and Grigaitis, which was signed by all 14 of the rescued people: Israel Gelas, Chazia Geliene, Rachel Gelaite, Jacob Gelas, Codik Bleiman, Boruch Intriligator, Akiva Zaitsev, Abram Rafaika, David Richman, Riva Kaganiene, Jacob Kagan, Genoch Kagan, Itzik Michelson.