The couple, who moved to New Zealand from Britain more than a decade ago, have two other children.
"It's going to be hard forever," Mrs Roberts said. "My baby has just got her first car and it's a nightmare every time she drives off. The roads are littered with white crosses; it's heartbreaking to see it."
Mr Roberts said the minimum driving age should be 17 and a zero tolerance approach to alcohol limits should be universal. He believed a limit to the type and power of cars young motorists were able to drive should be applied and those convicted of driving offences should not be able to obtain temporary licences. "It's an absolute dilution of the law and of delivering any consequence. That you can lose your licence and within a week apply for a day licence to get to work is nonsense. If you lose your job, well, that's tough but that's the consequence of breaking the rules."
Driving at night and on motorways should also have tougher rules, he said. "Most new drivers pass their tests on suburban roads, and getting out on to back roads at night time and on motorways can be completely different."
Gacitua was sentenced to three years' jail and disqualified from driving for four years after the crash that killed Fay. Although he was under the drink-drive limit, the judge ruled alcohol was an aggravating factor.