Waist not: Marilyn and Bob Birnhak , co-founders of the Philly Weight Watchers franchise, will be feted for their area philanthropic work at the Philadelphia Theatre Company's annual gala on April 30. Need "Stars" say take it easy on the hors d'oeuvres? ... She's so fine: Joy Cheryl Fine will have a one-person show of her art at Congregation Beth...