They've collaborated on a few music videos, but now, "Dance Moms" star Maddie Ziegler and singer-songwriter Sia are taking their partnership to a new level. The musician-turned-director is exploring film as a new medium, and she's tapping her frequent muse Ziegler to be at the center of her new project.

According to a report from Hollywood Reporter, the film will be called "Sister." The plotline is based on a short story Sia penned eight years ago. Sia opened up about the project during the Venice Days, a side event at the Venice Film Festival.

"I was too embarrassed to tell anyone I wanted to make a movie because I thought it would be seen as a vanity project because I was a singer," she told the crowd. "And then last year, after I made the 'Chandelier' video, I realized that I was pretty good at directing, so I felt a little bit braver."

As a new player in the film industry, Sia turned to experienced friends to help her fine-tune her work. The singer said she first sought help from "a guy from a juice bar" with a background in film, before spending over three weeks working on the screenplay with friend and children's book author Dallas Clayton. Other pals who gave feedback were comedian Whitney Cummings, actor Joel Edgerton and her husband Erik Anders Lang.

Details of the movie have not yet been revealed, but Sia disclosed that Ziegler will be the star of the film, according to Design & Trend.

The talented pair became close after their partnership for several music videos. In an interview with Harper's Bazaar, 12-year-old Ziegler shared more about their relationship, saying that even on days they don't have projects together, the two make time to hang out and watch television together.

"We started working together because she's actually a fan of our show 'Dance Moms,'" Ziegler told Harper's Bazaar. "She tweeted me and said that she would love to work with me and she wants me to be in her new music video for 'Chandelier,' which was her new song at the time."

She added, "We're like best friends, we're always hanging out and when I go to her house she's so sweet, she's like my sister or my mom, she is always caring for me. I love her a lot."

Now, the two are tackling a new journey together with "Sisters." While it means brighter things for Ziegler's flourishing career, it creates a lot of questions about her return to the reality show "Dance Moms." A previous report from Latin Post have already questioned her future on the Lifetime series to pursue other projects.