Europa was one of Zeus's lover, too. She was also related to Io. She was Io's great-great grand daughter, based on the family tree below.  Zeus fell in love with her. He approached her in the form of a white bull and carried her away from Phoenicia to Crete. She bore three sons for Zeus. 

Edith Hamilton was a German-American educator. The New York Times has described her as the Classical Scholar who "Brought into clear and brilliant focus the Golden Age of Greek life and thought . . . with Homeric power and simplicity in her style of writing". She wrote the book, Mythology, based on her study of Greek and Roman myths. The explanations of two stories above were based on her book.