German players Angelique Kerber, Tatjana Maria and Laura Siegemund have been given wild card entries for next month’s Porsche Grand Prix along with former US Open champion Emma Raducanu, organizers said on Thursday. Former winner Siegemund and Maria were given direct access into the main draw of the star studded field by the tournament because they would not be able to play in qualifying due to Billie Jean King Cup duty for Germany in Brazil. The team event tie is on April 12 and 13, and the Stuttgart indoor clay event follows April 15-21. “We go to great lengths to decide who we want to suppo…