The Bay Street Theater in Sag Harbor will hold auditions for upcoming concerts on Feb. 27 from 11 a.m. to 2 p.m., by appointment. The theater is looking for female and male vocalists to sing “in the style of Grace Slick and Marty Balin,” for a 30-minute set of Jefferson Airplane’s greatest hits, to be backed by a full band. Vocalists have been asked to prepare to sing “White Rabbit” and “Somebody to Love.”