NEW YORK -

Stephen Colbert and the cast of "Modern Family" are the next substitutes for Robin Roberts on "Good Morning America."

Roberts is scheduled to undergo her bone marrow transplant this week.

The surging ABC morning show revealed more details of its plans to deal with the extended absence of co-host Roberts, who needs treatment for a blood and bone marrow disease.

Senior Executive Producer Tom Cibrowski says the celebrities will be used in much the same way as Jessica Simpson was last week. They'll appear during the show's second half hour, which is heavy on pop culture.

Newswomen Barbara Walters, Diane Sawyer and Katie Couric should appear next month.