Please, don’t tell me they sing “Lotteroo”.
My Swedish uncle (distant, on my mom’s side) was an exec with their Swedish Record Company SKR (Svenska Köttbullar Rekord), and he told me they broke up on his and his company’s advice (he was a lawyer) to avoid a lawsuit over plagiarism from an Estonian group which originally composed and recorded, in the Soviet Estonia at the time, much of the material which Abba presented as their own.