Anastazy and Maria Dulski lived with their daughters Jadwiga and Wanda near Włocławek, where they had their own estate. After the outbreak of war, the property was seized by the German authorities. For this reason, the whole family moved to Warsaw. In the summer of 1943, a young Jewish girl, Basia Halbersztat, came to them for help. She was referred to the Dulskis by Janina Kulwieć. The family took care of Basia and treated her as a family member. One day, a neighbour informed the Dulskis that he had overheard a conversation in a shop that Basia, who lived with them, was of Jewish origin. The woman, in order not to endanger her guardians, suggested that she leave. Maria strongly criticized her idea, because the girl had nowhere to go, and moreover, her disappearance would only confirm the suspicions. That same evening Maria took Basia to this neighbour and categorically denied the words she had heard. Afterwards, the women and the neighbour went to the shopkeeper to explain the whole situation, obtaining an apology from the man. Despite this one-off incident, they managed to hide Basia until the Warsaw Uprising. The Dulski family also hid other people of Jewish origin, such as Henryk Rotbart, a lawyer, and Stefan and Janina, a married couple from Kraków. They also helped Basia’s brother Dawid Halbersztat. Thanks to the help of the whole family, all those under their care managed to survive until the end of the war. Basia and her brother emigrated to Israel and Henryk Rotbart to Australia.

The Yad Vashem Institute awarded Anastazy and Maria Dulski together with their daughters Jadwiga Adamska and Wanda Pawłowicz the title „Righteous Among the Nations” on 23 April 1975 for helping Jewish people during the Holocaust.