On March 15, Roz Ryan, who has been co-starring in the WB sitcom “All About the Andersons,” returns to the role of Matron “Mama” Morton. Ryan, a veteran of the Broadway and national touring companies of the Kander and Ebb musical, will stay with the production through Sept. 12.

And, the following week, Christopher Sieber, who can currently be seen in the ABC-TV series “It’s All Relative,” will make his Chicago debut as Billy Flynn. Sieber will play the slick lawyer March 22 through May 2.

Ryan made her Broadway debut in the Fats Waller revue Ain't Misbehavin'. She also starred on The Great White Way in Dreamgirls and One Mo' Time and in the national tours of Annie, South Pacific and Blues in the Night. Ryan's film credits include "Went to Coney Island," "Cotton Club" and "Dark Indigo."

On Broadway Christopher Sieber has been seen in Thoroughly Modern Millie, Into the Woods and Triumph of Love. His other theatrical credits include Boys in the Band, A Christmas Carol, Pal Joey, The Music of Andrew Lloyd Webber and Meet Me in St. Louis. Sieber’s television credits include “Two of a Kind,” “Sex and the City,” “Ed,” “All My Children,” “Another World” and “It’s All Relative.”

Chicago won the Tony for Best Revival of a Musical in 1997 as well as awards for actors Bebe Neuwirth and James Naughton, director Walter Bobbie, lighting designer Ken Billington and choreographer Ann Reinking. The original production was directed and choreographed by the late Bob Fosse. The Ambassador Theatre is located at 215 West 49th Street.