Yad Vashem, the Holocaust Memorial institution in Jerusalem has a searchable database of Holocaust victims. They just passed 5,000,000 names and have some hope of being able to recover 250,000 of the remaining one million. I searched the database and found the names of my mother's mother and teenage sister:
https://collections.yadvashem.org/en/names/9151952
https://collections.yadvashem.org/en/names/9151953