Come on… Orlando couldn’t do a live stage version of the musical Mamma Mia? They could honestly just have Donna and the Dynamos (augmented by Sam, Harry, and Bill - like during the curtain call) give performances of Abba music and call it a day.
It’s worked for Blues Brothers for 35 years.
I’m still annoyed they never had the Barden Bellas from Pitch Perfect perform…