The film debuted at the Cannes Film Festival and includes interviews with Houston's half-brother, the former NBA basketball player Gary Garland-Houston, and her assistant, Mary Jones. This latest film on the late singer features interviews with many of Houston's relatives and close acquaintances, two of whom make the claims against Warwick.
The Warwick family has been contacted for comment by the BBC.
Macdonald went into making this documentary with the initial hopes of cleaning the tarnished, addiction-riddled image of Houston that plagued her later years until her sad and untimely death.
Bobbi Kristina with her family in the 2005 Bravo reality series "Being Bobby Brown". [Her estate] entrusted me with the 'keys to the vault' while giving me complete freedom to follow the story wherever it went.
"I just felt she was so condemned towards the end of her life, so under-appreciated, that it seemed a good time to look at her career again", said Broomfield.
To understand Whitney Houston, it must be remembered that his mor, Cissy Houston, was a singer, better known for being a showgirl of big stars like Aretha Franklin or Elvis Presley, with his parents recently divorced after birth of Whitney, small of three Siblings, in Newark, new Jersey, children's childhood was spent in or family homes during maternal tours. "So I think it was the combination of thinking there's this really interesting personal mystery, but also how this woman was a musical genius", he explained.
"She had tears in her eyes", Jones said.
According to her family, Houston "was ashamed" to tell her mother of the abuse. "It was kind of a detective story to get that piece of information, which changed how I felt about Whitney and how I felt about the story", the filmmaker continued.
"That was just an intuition, and then somebody mentioned it off-camera to me".
"She doesn't enjoy her own body in some way".
In the documentary, Jones recounted a conversation she had with Houston before her death.
He added, "I'd been watching her for several months and saying to editors, 'There's something about her that reminds me of something'". "My mom was a little tough on Whitney because she knew what Whitney had", said the singer's brother. "It will lift the burden off you'".
Singer Whitney Houston, left, and her daughter Bobbi Kristina arrive at the Pre-Grammy Gala & Salute to Industry Icons in 2011.
In it, it's said the troubled recording artist had a relationship with a female partner, called Robyn Crawford, but it was a struggle for her.
Whitney, which is to be released in theatres July 7, suggests that the alleged incidents of abuse took place while Cissy Houston was touring.