The project, which is currently untitled, stars Nathan Lane as an unfortunate actor called Jasper who returns home to Texas when his father becomes ill.
Rhea has now signed up to play Jasper's sister Emilia, Deadline reports.
Rhea has previously appeared in shows such as Pride & Joy and Sabrina The Teenage Witch.
Elsewhere, Jackson - who recently played Dustin Goolsby in Glee - will play Jasper's new friend Tim and Scrubs star Ken Jenkins will appear in the project as Jasper's sick father.
Richard Kohnke has also been cast and will play Emilia's son, while Laura Bell Bundy will guest star in the pilot as Tim's wife.
Other projects currently in the works at USA include a drama about federal agents and a remake of British comedy Sirens.