WATCH BELOW: Campaign to change Australia Day from January 26On Monday night, the 36-year-old singer-songwriter shared a series of snapshots from her rehearsal for 2021's Australia Day celebrations.Taken on the stage on the iconic Sydney Opera House steps, the photos show Delta singing alongside her boyfriend and fellow musician, Matthew Copley. "And we‘re back!! (Or did we ever leave this beautiful @sydneyoperahouse over Christmas ha!) Rehearsals for tomorrow night’s @australiaday26 concert