Isla's cancer was diagnosed in the Thai capital Bangkok, where she was treated for about six months with chemotherapy.
"In October 2016 we were allowed home - back to our island."
Isla was well until the end of 2016, when she relapsed and began a second session of treatment, which went on for about a year. That included a stem cell transplant from Andrea.
"She was fine for ages, she was doing really well ... we all thought everything was fine. She had a few issues with GvHD [graft-versus-host disease], which is a side effect to stem cell transplant, but basically she was doing okay.
"Then out of the blue last Christmas she just went for a scheduled check-up and the blood tests were terrible, so bad the doctor couldn't believe it had happened. So we asked for a second blood test and that confirmed the worst, that she had relapsed again."
"The doctor told us there was nothing he could do and that we should take her home."
"We decided because the doctors there [in Bangkok] couldn't do anything, to bring her back to New Zealand so she could be with her family."
"We were told she would have about four months to live, but she just got worse and worse really quickly and then on the 18th of January she passed away."
Isla had arrived in New Zealand on January 10 and was admitted to Starship children's hospital in Auckland for two nights before going home to her family in Greenhithe.
"She died in a lot of pain. It's very hard to believe it's happened," her father said.
"She was called Isla Smiler before she got sick … because she was just such a happy little thing.
"Isla and Lulu were just so close and sweet and Isla adored her sister more than anything in the world."
Jim said Isla wouldn't go anywhere without her toy dog Sunny.
"We had a dog called Sunny, so the cuddly toy was her dog, but the dog died about a year ago."
"She ended up dying with Sunny in her arms, so when we cremated her we cremated them together, the little cuddly toy."
"She was just a bubbly little bean, she was an inspiration to lots of people. She was the happiest little girl and funny, and she was too young to realise how sick she was.
"She was so brave as well. She never moaned about her sickness. She would take her jabs, her blood tests without any crying; all the doctors and nurses were amazed that she was like that.
"Even when she was sick, 102 degree [38.9C] temperatures with brain problems and she would still smile for us."
Jim said Isla's treatment cost a fortune. Insurance had covered many costs and crowdfunding campaigns had helped, but he hadn't worked for three years and most of the family's savings were now gone.
Crowdfunding had provided the money "so we can go back to Thailand and sort things out before we probably come back to New Zealand and start again".