The stars posed as buskers for an undercover live performance in New York City.
The 24-year-old singer debuted new music on Friday.
During an interview with Elvis Duran, the 17-year-old joked she could join the group as the fifth member.
The couple has returned to Miley's family home in Tennessee.
ET caught up with Billy Ray on the red carpet at the 2017 CMT Music Awards, where he gushed over his daughter spending the week at home, and revealed Liam has been there 'quite a bit.'
ET was on the ground as some of music's biggest stars poured their hearts out onstage for the victims of the Manchester terrorist attack.
Williams, Mumford and Cyrus came together on stage during Ariana Grande's One Love Manchester benefit concert on Sunday.
The 'Dangerous Woman' singer made her return to Manchester two weeks after the attacks.
'All we feel tonight is love, resilience and positivity,' the 'Happy' singer said.
The pop star returned to London for the first time after the tragedy at her Manchester show.
Ariana is back in London to raise money for the families of victims at her Manchester concert on May 22.
ET is on the scene as the concert shapes up. Ariana Grande, the Black Eyed Peas and more will perform.
Katy Perry, Justin Bieber, Miley Cryus and a Manchester school choir will also perform during the show, which will air live on the BBC.
The star-studded show will benefit the victims and families of those affected by the horrific bomb attack at her May 22 concert.
