Pierre Bonnard's wife had four unknown nieces; a French court ruled in 1951 that he forged her will, and the family won on appeal

Pierre Bonnard's wife Marthe, who died in January 1942, had told him for decades that she had no family. After Bonnard died in 1947 without children, the estate opened and four nieces appeared, the daughters of Marthe's sister, among them Aline and Marguerite Bowers. They claimed half the estate, including the roughly 700 works in his studio. Le Journal des Arts reports that after Marthe's death Bonnard, on his notary's advice, signed a false estate declaration so the studio works would not be lost. In 1951 a court found Bonnard posthumously guilty of forging the document and ordered his family to hand half the estate, about 700 works, to Marthe's heirs. The Bonnard side appealed and won, arguing he did not know Marthe had relatives. The case reached the Court of Cassation, and Time reported it on 9 March 1959. Le Journal des Arts reports that art dealer Daniel Wildenstein bought the rights of Bonnard's heirs for $1 million, argued the painter's moral right over his work, and won; he took all studio works except 25, kept about 180 and gave others to the family. That account rests on Wildenstein's own memoir, as cited, and is single-sourced^†. The Cleveland Museum of Art records that the Bowers sisters inherited several paintings after a long legal battle. MoMA stated in 1964 that the litigation had run from 1947 until 1963.