Muhammad Ali's daughters in London to promote 'I Am Ali' documentary  

Step-sisters Maryum and Hana Ali plan to visit their 72-year-old father in Arizona on their return from London and sit down to watch it with him — in silence.

"If you even speak when you watch anything to do with him, he'll say 'Shh,'" Hana said Tuesday with a smile.

"I Am Ali" mixes interviews with Ali's family and inner circle, with archive footage and personal audio recordings. Maryum and Hana both feature, looking back at their childhood years with Ali.

"For me it was bittersweet," Maryam said. "He was famous in boxing when I was a kid. I had to share him with the world, at the same time the world loved him. so we were able to receive the love."

And despite the fact she used to "come home to Michael Jackson sitting in the living room", Hana adds that Ali made sure his children stayed down to Earth.

"I grew up going to school and bragging a lot 'my daddy is Muhammad Ali, I can do what I want to do,'" she said. "And he used to sit me down and tell me how just because I'm famous the world's going to treat you different. They're going to treat you special, but you're no better than anybody else and the only thing that makes you greater than anyone is your heart.'"

Ali, who has been suffering with Parkinson's disease since the 1980s, is enjoying life and doing well, his daughters said.

Ali "enjoys his life. He's at peace. He gets good care," eldest daughter Maryum said.

When the media speculates about Ali's health, the former boxer asks his daughters "Did I make the front page?" according to Hana, Ali's daughter with Veronice Porche.

"He's so funny. He's like 'I'm not dying.' I think he thinks he's going to live forever."

Maryum reassured fans that "unless it comes from the children or his wife, you can't believe anything you hear about his health."

"I Am Ali," by filmmaker Clare Lewins, will be released in Britain on Friday.