03/06/2012 at 11:00 AM EST
With her mom Demi Moore out of treatment
and back in Los Angeles, Rumer Willis
was all smiles Monday as she promoted her new movie at the Miami International Film Festival.
Willis, 23, attended the premiere of The Diary of Preston Plummer
, where she cut a glamorous figure in a curve-hugging dress.
"It was fun making the movie and fascinating working with Robert Loggia," she told PEOPLE of starring alongside the longtime character actor in the film. "I wasn't in many scenes with him but it was cool being around so much wit and wisdom."
It was likely a relief for Willis to focus on professional duties. The oldest daughter of Moore and Bruce Willis may have been present
for the 911 call that sent her mother to the hospital back in January, and has taken an active role in keeping the family together in Moore's absence.
Rumer attended her younger sister Tallulah's 18th birthday bash
last month and reportedly encouraged Moore's estranged husband, Ashton Kutcher
, to visit Moore during her treatment