Urie will play the role in the Tuesday, July 10 performance at 8pm, with Davis taking on the role during the 4:30pm and 8pm performances on Wednesday, July 11.
As previously reported, It's Onstars Jenna Leigh Green and Colin Hanlon as a pair of songwriting partners who have been given the chance to record a theme song for a new televsion show. Curt Hansen, Sheryl Lee Ralph, and Mindy Sterling also star.
Davis starred on Broadway in Chicago and Boeing-Boeing and is best known as a television personality and reality show host.
Urie starred on Broadway in How to Succeed in Business Without Really Trying and Off-Broadway in The Temperamentals. He is best known for his work on ABC's Ugly Betty and will be seen in the new sitcom Partners.