Deacon and Gill are joining the classic rock band as the group gets ready to headline a two-part music festival event, Classic East and Classic West, with concerts in Los Angeles and New York City.
The new additions will be working together to cover Glenn's vocals on a number of Eagles songs including "Peaceful Easy Feeling," "Already Gone" and "Lyin' Eyes."
"While I was still in shock during some interviews after Glenn passed away, I did say that I thought that was the end of the band," member Don Henley said while speaking with The Los Angeles Times. "But I reserve the right to change my mind. Ralph Waldo Emerson said, 'A foolish consistency is the hobgoblin of little minds.'"
"In my mind, I always thought I'd have made a good Eagle," added Gill who previously worked with Henley on a country album and participated in the Eagles tribute concert at the Kennedy Center. "But in a million years, I never would have seen this coming."
Deacon has said that he grew up singing songs with his father and learned how to play "Take It Easy" and "Peaceful Easy Feeling" on guitar at an early age. "They came to me with the idea, and it's been really great," the 24-year-old said about being approached by the Eagles.
Classic West takes place July 15 and 16 with Classic East arriving July 29 and 30. The concerts will also feature performances from Fleetwood Mac, Earth Wind & Fire, The Doobie Brothers, Journey and Steely Dan.
Glenn, the guitarist for the Eagles, died of complications from rheumatoid arthritis, acute ulcerative colitis, and pneumonia in January 2016 at the age of 67.