Did Melonie Diaz (Mel), Sarah Jeffrey (Maggie) and Madeleine Mantock (Macy) go down Google wormholes of research while preparing to star as sisters in The CW’s “Charmed”? And, find out which of the stars is a big “Harry Potter” fan. Plus, the actresses dish on what their excited to explore as the series rolls out. “Charmed” premieres Sunday at 9/8c on The CW.