Halston, who previously appeared in the play by Nora and Delia Ephron, was last seen in the Off-Broadway run of Charles Busch's The Divine Sister. Along with Bergl ("Desperate Housewives") and Morris ("The Electric Company"), Halston will join Emme and Susan Sullivan for the June 10-July 3 cast.
Zuzanna Szadkowski ("Gossip Girl") will be part of the July 5-Aug. 7 cast, which will include the previously announced Alison Fraser and Marla Maples.
The current cast features Conchata Ferrell, Minka Kelly, AnnaLynne McCord, Anne Meara and B. Smith, who appear through May 29.
Karen Carpenter directs the Ephron's production based on Ilene Beckerman's book of the same name that "uses clothing and accessories and the memories they trigger to tell funny and often poignant stories that all women can relate to."
The design team includes Jo Winiarski (scenic design), Jessica Jahn (costume design), Jeff Croiter (lighting design), Walter Trarbach (sound design) and Maria Verel (make-up design).
Carpenter also directed the Monday night readings of Love, Loss, and What I Wore that were presented as a benefit for Dress for Success. A portion of the proceeds from the current run benefits Dress for Success.
For tickets phone (212) 239-6200 or visit Telecharge. The Westside Theatre is located at 407 West 43rd Street in Manhattan.