Line of Judith and Emma of Bavaria

(1) Count Welf of Alemannia married Heilwig and had daughters Judith and Emma. (2) Emma of Bavaria married Louis II, "the German", King of East Franks, while her sister wed Louis II's father, Louis I. Thusly Emma was Judith's daughter-in-law as well as sister, and their children were cousins and half-aunts and uncles!