Eventually, she stopped drawing too, and her art was stashed away by Susan's mother and grandmother until two of her sisters unearthed it 20 years later.
The documentary features footage and photographs taken by Robin's father, and is woven together with recent interviews with the family and footage of Susan.
"I know some little nephews and nieces find it very exciting, seeing themselves and seeing their parents and aunts and uncles, and all the old family movies," said Robin.
Robin, who has lived in Carterton for six years and has another sister, Heather Bannister, living in Masterton, has strong memories of Susan's drawings.
"She drew every day. Often when we went to bed she'd still be up drawing because she was older. It was exciting to go out in the morning and see what she had drawn. Sometimes she'd drawn naked bodies and we'd giggle at the rude pictures."
Director Dan Salmon tracked the family as Susan's art started to gain notoriety from 2008, and finished the film just two weeks before the NZ Film Festival opened in Auckland.
When he first approached the family, Susan was not drawing - but as her artwork gained momentum, she started again.
"I thought it was retrospective with a sad ending, but it changed from a story of loss to one of redemption and healing."
Mr Salmon said he watched Susan grow as she began to draw again.
He said that when Susan stopped talking, she expressed herself through art, but when that stopped, there was a silence.
"When she started drawing again, it was healing."
