So it's no surprise that Ringer will introduce another person in Siobhan's sphere — a former friend to be played by Madchen Amick (Twin Peaks, Gossip Girl), reports TV Line.
Amick will play Greer Sheridan, a “confident, sexy and strong-willed” fellow socialite who was once very close to Siobhan. When twin sister Bridget works with her on a charity event, she tries to discover exactly what happened to cause a rift between the former besties.
Look for Greer to show up in episode 11!
Source: TV Line