"Greetings From Broadway" is a promotional week taking place April 1-7, sponsored by The League of American Theatres and Producers Inc., the trade organization for Broadway and touring Broadway across the United States and Canada.

For her Broadway debut, Vieira will appear in several scenes throughout the show, assuming the roles of Daphne, a Dishwasher, the Speed Tappist and more. She'll sing, dance and act, a spokesman said, and have a relationship with Actors' Equity for one week. (No actor loses pay for the roles Vieira assumes.) She's learning her dance routine in the days before stepping in.

The Millie and Vieira pairing is an isolated promotion for the week. Don't expect Star Jones to step into Aida or Barbara Walters to ride the mechanical bull in Urban Cowboy.

In addition to Vieira's appearance, "Greetings From Broadway – Fan Appreciation Week" affords "Broadway fans the opportunity to enter a special sweepstakes with prizes including tickets to Broadway shows, airline vouchers, hotel accommodations, dining, shopping sprees and more." For more on the "Greetings From Broadway" program, visit www.ilovenytheater.com.

Tickets for Thoroughly Modern Millie can be purchased by calling (212) 307-4100. The Marquis Theatre is at 1535 Broadway at 46th Street.