The Picton teen’s aunt said “there are no words” to describe the tragedy and posted a photo of herself and her daughter on social media.
A cousin also posted about Cunningham’s death.
“Our whānau lost a beautiful soul,” she said.
Others who knew Cunningham described her as “a beautiful young woman” who would be “missed greatly by all”.
Police said support was being provided to victims’ families and the survivors, who suffered moderate injuries.
An investigation into the cause of the crash is under way.
“It really is a tragedy,” Marlborough District Mayor Nadine Taylor said.
“I don’t think anyone can hear news like that and not have their hearts go out to the families. You start the day and your family is all intact and somewhere along the line, the family is going to get news that will change their lives.”
She said the community was with the families of the victims.
It is understood the two other victims — teenage boys — were also from Picton.
Tributes are being posted for them online by friends.