The eight-year-old daughter of Dubliner Tom Hand - who was believed to have been killed by Hamas at a kibbutz in southern Israel on 7 October - could be alive.
The family told RTÉ News that the Israeli Defense Forces now believe there is a "high possibility" that Emily is being held hostage in Gaza.
Hamas attacked Kibbutz Be'eri killing more than 100 people, with more than 70 listed as missing.
The Irish Embassy to Israel has confirmed that Emily is believed to have been abducted and not murdered on 7 October.
An embassy official said the revelation was based on DNA tests which indicated that Emily was not among those whose remains were found at Kibbutz Be'eri, which has led Israeli police to believe she could still be alive and held hostage in Gaza.
The Times of Israel reported that Emily's half sister Natalie had made a direct appeal to her captors through Channel 12, a private Israeli channel.
"We were told that she had been murdered. We were in mourning," the Times of Israel reported Natalie as saying.
"On 31 October, they told us that it was highly likely that she had been abducted."
In a direct message to her half sister, Natalie added: "I want to tell you that we are doing everything to get you home. We know you are being held hostage. We love you so much and miss you."
The Department of Foreign Affairs said it is aware of the case of Emily Hand and is providing consular assistance to her family.
Additional reporting: Tony Connelly in Tel Aviv, and PA
