How was Fridlevus II related to Halfdan?
Fridlevus II Fridleif (Ynglinga saga) was a son of Fróði of the Skjöldung (Scylding) lineage. In that work he was the brother of Halfdan and the father of Áli the Strong.
Astrid Olofsdotter of Sweden Astrid Olofsdotter (Norwegian: "Astrid Olavsdatter"; English: "Aestrith") (died 1035) was the Queen Consort of King Olav II of Norway.