They were born in Melbourne after Jonathan and his former partner Selina Korenhof moved to Australia in 2012.
She and his family are trying to bring his body home for burial - but flying everyone back to New Zealand so close to Christmas was too big a cost to shoulder alone.
"It's so expensive - more than what I assumed," Korenhof told the Herald.
Jonathan's family is fundraising to cover the costs of bringing his body and his family back home to Whakatane.
They hope to bury him on Christmas Eve, if not earlier.
His mother and a sister were in Melbourne preparing his body, but his dad was "just waiting for his boy to come home", Korenhof said.
"His dad is probably taking it the hardest because he's not here."
Her father started a Go Fund me page, which has attracted nearly $3000 in donations - $1000 short of their goal.
"I loved him like he was my own son," he wrote in an emotional plea for help bringing Jonathan home.
A flight has been booked to bring his body back, and his family hoped to join but weren't yet able to afford tickets.
Korenhof remembered her husband, who she separated from a year ago, as a fun-loving and super-active person who was dearly loved by his friends and family.
"He was such a sweetheart; he had such a sweet heart," she said.
"We had our separation, but he was always there for the kids. And I'm so glad."
She didn't want anyone else to die from preventable complications from diabetes, saying anyone living with the illness should remember to look after their health.
Back in Whakatane, friends and whanau were packing out Jonathan's family home, waiting for his arrival.
Going home for Christmas would be bittersweet, she said.
"We'll be back there to celebrate Christmas and New Years with our family, but under these circumstances."
To donate to help Jonathan Korenhof's family come home to bury him, click here.