Maddie Ziegler has described her mentor Sia as her ''second mom''.

The 15-year-old actress-and-model has appeared in a number of the singer's music videos, on her album covers and more and she will star as a younger version of the 41-year-old songwriter in upcoming biopic 'Sister', and filming has brought them even closer together.

Speaking to PEOPLE magazine at the WSJ. Magazine's 2017 Innovator Awards, Maddie said: ''I've actually lived with [Sia] this year more than I have with my actual family, so it's fun. We have the best time together. She teaches me how to cook and new things about life ... It doesn't feel like work when we're together anymore. It's really just a bond that we have. She's my second mom.''

Although the pair worked together on the promos for hit singles 'Chandelier', 'Elastic Heart' and 'Big Girls Cry', Maddie admits making a film was a very difference experience for them both.

Maddie - who will appear alongside Leslie Odom Jr. and Kate Hudson in the movie - said: ''It was such an incredible experience getting to work with Kate [Hudson] and Sia. I always work with Sia as a director, so that wasn't something new, but her directing us for Maddie previously heaped praise on Kate, and made it clear it was a huge deal to be appearing alongside the 'Almost Famous' star.

She recently told 'Entertainment Tonight': ''She's amazing I mean she knows how to do everything, she's the most incredible actor and she's probably my biggest inspiration in life - her and Sia, two girl empowerment, they're amazing.''