Complex sentence: Kasprowiczowa and Aniela Pająkówna, one of whose two daughters was Przybyszewki's, while Dagny had romantic relationships with at least three men in Paris, including Emeryk.
Split into simpler sentences: Kasprowiczowa and Aniela Pająkówna, one of whose two daughters was Przybyszewki's. Dagny was carrying on affairs with three men in Paris, including Emeryk.