Jarosław Iwaszkiewicz and his wife Anna with their daughters Maria (born 1924) and Teresa (born 1928) lived in the estate in Stawisko in Podkowa Leśna, located at the border of Brwinówek and Milanówek near Warsaw. Iwaszkiewicz – a writer and a columnist in the periodical Wiadomości Literackie – and his wife had wide contacts in the circles of Polish intelligence of Jewish origin. During the German occupation they helped many former neighbours, friends and acquaintances – they hid them, found new shelters, provided with funds and false documents.
Iwaszkiewicz was active in the structures of the Underground Poland, took part in saving the objects of Polish cultural heritage. Their house was a shelter for those in danger of arresting and war orphans, particularly after the fall of the Warsaw Uprising.
In Stawisko, the Iwaszkiewiczs hid the Muszkats, and when the elderly couple was in danger, they organized moving them from Podkowa Leśna to Milanówek. The Muszkats were hidden by Jerzy Mieczysław Rytard (1899-1970), a friend of the Iwaszkiewiczs. In 1968, Iwaszkiewicz described vividly the circumstances of that journey, during which the Muszkats "did not know what was going on with them and, for unknown reasons, they started speaking French." After that, Delfina Muszkat was placed in the hospital in Grodzisko, whilst her husband was cared for by "a kind peasant or a craftsman displaced from Poznań who lived between Grodzisko and Milanówek." Iwaszkiewicz recalled that "He died calmly; I saw his host planing boards for a coffin for him, and his tears were falling on wood chips." In the Iwaszkiewiczs house, their daughter, Aniela Neufeld (Nowicka) with her daughter, Janina Nowicka, spent often nights. The Iwaszkiewiczs supported them financially and provided with food, whilst Aniela – Maria Curie-Skłodowska's pupil – taught the Iwaszkiewiczs' daughters physics.
The Iwaszkiewiczs also supported their acquaintances from Brwinów: Wiesław Gelbart and his father Michał. The father was hidden on the premises of the estate, whilst Wiesław was installed in Boglewice estate in Grójec district.
The underground classes in the Iwaszkiewiczs' house were attended, apart from Aniela Nowicka, by the former assistant of Curie-Skłodowska, a renowned physician, Professor Ludwik Wertenstein (1887-1945) and a historian, Professor Marceli Handelsman (1882-1945). The Iwaszkiewiczs helped also Wertenstein's daughter – Wanda, who they provided with funds and food.
Anna Iwaszkiewicz also supported the brothers, Mojżesz (Marian) and Natan Karwaser – sons of Jankiel and Chawa nee Frenkiel – the former neighbours from Brwinów – the sons of owners of the coal stock which provided the Iwaszkiewiczs' house with coal before the war. Shortly before the outbreak of the war, Anna Iwaszkiewicz sold them land in Podkowa Leśna but a relevant notary deed was not prepared. When the Karwasers were sent to the Warsaw Ghetto, Anna used to bring them money to the ghetto, handed over in the Courts building on Leszno Street. She also helped them to obtain the so-called "Aryan papers". Both brothers survived the war, Natan with his wife Bracha and daughter Ewa, born in 1946, left to Israel, whilst Marian Karwaser (Komarczyk) had warm contacts with the Iwaszkiewiczs.
Anna Iwaszkiewicz also took care of the Kramsztyk family: Andrzej and Irena and their daughter Joanna. Initially, the Kramsztyks hid for two years under the name of Krawczyk in Kobyłka near Warsaw. However, in spring 1943, they had to escape from there. In Warsaw, their remaining funds and clothes were robbed. At that time, they found shelter in Milanówek, with Andrzej's sister and mother. Andrzej had not left the room for two years, where the Iwaszkiewiczs provided him with clothes and food, whilst his wife and daughter lived in the flat of the estate's workers. When Joanna was in urgent need of the operation of the vermiform appendix, Anna arranged it for her with her relative – the surgeon Stanisław Lilpop. In 1987, Joanna Kramsztyk Prochaska wrote: "The awareness itself that they took care of us helped us to live." After liberation, both families remained sincere friends.
The Iwaszkiewiczs' daughter – Maria Iwaszkiewicz-Wojdowska – underlines in her report: "For my parents, helping people in danger was so natural that they did not seek any distinctions or awards."
In 1988, the Yad Vashem Institute awarded Anna and Jarosław Iwaszkiewicz the titles of the Righteous Among the Nations.