Middleton's parents feared she'd now be deported from the country without completing her sentence.
Judy Richards said it wasn't fair she'd been robbed of a son, while Xiao got to return home to her family.
"Rhys would have been turning 24 on the 15th of September. Jieling gets to go home to her family and live out the rest of her life.
"We will all be suffering for the rest of ours," she said. "It is sometimes too much to bear."
Mike Middleton said he could never forgive Xiao for getting on the road, knowing she wasn't a good driver.
"The cops said she would never have made Taupo, without killing someone or herself," he said. " I don't call it an accident."
Richards and Middleton both wanted Immigration New Zealand to ensure those who committed a crime served their time before being deported.
"It doesn't matter who you are, you got to do your time," Middleton said.
Richards said if Xiao was truly remorseful she'd not have appealed her sentence.
"If I'd killed someone in another country I'd expect to do the time," she said. "She needs to take ownership of what she's done and show some remorse.
"Why should she get away with it? She killed a young man, a son and brother who was in the prime of his life. What price do we put on the life of a loved one?
"We need to get immigration to allow these people to serve their home detention," she said. "Because at the moment my understanding is if they do a crime, they get served notice and then they get a free ticket home."
On Tuesday, Xiao's lawyer appealed her prison sentence on the basis that it was her inexperience not "dangerous driving" that led to the crash.
In a decision released today, Justice Jillian Mallon granted the appeal and reduced Xiao's sentence to nine months' home detention and 150 hours' community work.
While Mallon agreed with the judge who'd delivered the initial sentence that deterrence was necessary - she felt home detention was more appropriate.
She said the preceding judge's concerns that the Chinese woman would be deported should not have had any bearing on the final sentence, but rather that it was the gravity of her actions that should have been taken into consideration.
Mallon said given Xiao, who had no prior convictions, had shown remorse, offered reparation and was considered to be at low risk of reoffending, home detention was more appropriate.
She added while Xiao should have known her driving was not safe, it seemed she was unaware she'd be putting other drivers at risk.
The judge said Xiao had also taken steps to account for her own lack of experience and confidence, by reading the road code, practising driving around town and practising driving on the open road the day before the crash.
Furthermore Mallon said there were no other aggravating features, such as aggressive driving, or alcohol or drugs, which often arose in a charge of this kind
"It was a case of inexperience and a lack of awareness of the dangers arising from that inexperience."
Therefore she quashed the jail sentence and taking into account the time already served in prison, reduced Xiao's sentence to nine months' home detention and 150 hours of community work.
