has revealed who will be filling in for Katy Perry and Lionel Richie as they complete their coronation duties across the pond.Alanis Morissette and Ed Sheeran will serve as guest judges on Sunday, May 7, alongside Luke Bryan, while Perry and Richie fulfill their duties, ABC announced Monday.Morissette will be pulling double duty as she will also be a mentor to the remaining hopefuls, who will be performing her songs live on stage. The contestants will also perform duets of Sheeran's popular songs.Both are also slated to perform. Morissette will take the stage to perform one of her classics while Sheeran, who will be celebrating the release of his latest album, — (pronounced ), will perform his new single.