How many Fanny Brices does it take to screw in a lightbulb? If you’re at Boiler Room Theatre, the answer’s at least a dozen. That’s how many will be on hand for this unique concert mounting of the 1964 musical that helped make Barbra Streisand the “greatest star” — with lyrics by Bob Merrill and music by Jule Styne, and featuring such theatrical standards as “People” and “Don’t Rain on My Parade.” Produced by Sondra Morton, BRT’s Keeping Scores series of Broadway musicals is modeled on the Encores series of New York City, with this inaugural effort directed by Scott Logsdon, with musical direction by Jamey Green and choreography by Lauri Gregoire. This and subsequent concerts will focus on shows that are not likely to be produced full-scale locally, and, ideally, the composers and/or artists involved with the original productions will make an appearance for audience talkbacks for some titles. Among the diva dozen are Nancy Allen, Erica Haines Cantrell, Stephanie Jones Benton, Cori Laemmel, Corrie Miller and Heather Trabucco. Featured players include Bakari King, Jama Bowen, Layne Sasser, Todd Rowan and Will Sevier, plus a choral ensemble of adults and children.