Angelina Jolie's son was a "big brother" to the young actors in 'First They Killed My Father'.
Maddox Jolie-Pitt
The actress-turned-director enlisted her oldest child, 15-year-old Maddox - who was adopted from Cambodia when he was a baby - to help with production on her latest movie and Loung Ung, whose book about the Cambodian genocide inspired the film, says he and his younger sibling, 11-year-old Pax, who was there shooting stills, were a great presence on set.
Loung told People: "I have watched the young people grow into really kind, empathetic, curious human beings.
"Pax is a talented photographer and Mad is so kind and generous. The cast kids, they all looked up to him as a big brother."
And the activist was "so proud" of her famous friend's sons because they were happy to make time to play witht he young children on the set and "make them laugh."
She added: "There were sad days on the set and there were difficult long hours. And to do it in an environment where people love and respect each other was exactly what we needed to get it done."
'First They Killed My Father' tells of how Khmer Rouge soldiers seized Loung's home town of Phnom Penh during the 1970s in a bid to purge the country of western influence, with those not killed sent to gruelling labour camps, and how her parents and two sisters died during the horrors
And the author and her surviving siblings "love and respected Angelina so much" that they knew she'd do justice to their story.
She said: "To have this beautiful film about family, to have this beautiful mother doing a film about family, I had complete trust that our story was in good hands. And my siblings felt exactly the same way. We are so honored and proud that this wonderful mother made this film about family.
"We all knew on set that this wasn't just a movie Angelina was making, but this is also in some respect her story -- her son's story.
"And she takes that seriously ... and so to make a film with somebody who truly loves this place, made the cast and crew, I think, allowed them to trust the experience."
Speaking at the premiere of the movie in Cambodia at the weekend, Angelina - who was joined by her six kids, Maddox, Pax,
Zahara, 12, Shiloh, 10, and eight-year-old twins Vivienne and Knox- admitted the film is her thank you to the country.
She said: "I cannot find words to express what it means to me that I was entrusted with telling part of the story of this country.
"This film was not made to focus on the horrors of the past, but to celebrate the resilience, kindness and talent of the Cambodian people. Most of all, this film is my way of saying thank you to Cambodia. Without Cambodia I may never have become a mother. Part of my heart is and will always be in this country. And part of this country is always with me: Maddox."
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