© BBC
Robinson, 18, finished fifth in Andrew Lloyd Webber's talent show earlier this year, one place behind Fearon.
The Middlesbrough performer will stand in for three nights in The Landor Theatre's production of Smokey Joe's Cafe, in which Fearon has been appearing since last month.
Fearon will miss the shows on August 20, 21 and 22 to have an operation on her wrist. Bookings for the production have now been extended to September 5.
