"It was a horrific time. Incredibly, our family friend was found to be a suitable donor at the very last minute," she said.
"The worst thing was not knowing what the future might hold - we just had no idea," said Mrs Morgan.
She emphasised how important it was meeting other families going through the same thing - people she calls her "liver friends".
"You become so close - it helps to stop feelings of isolation," she said, adding that Liam was now a healthy and happy 10-year-old.
He is one of 79 children who have received liver transplants in New Zealand since 2002. Fifty-five per cent of these have been from deceased donors, whose memory was honoured with the release of butterflies.
Samantha Sutherland, whose daughter Lara was given a liver when she was eight months old, said the memorial service was important for her family. "It's a chance to pay our respects and say thank you - where would we be without them?"
The event was organised by the Kids Foundation, which provides support to liver transplant children and their families.
The foundation is raising funds for a dedicated patient and family centre close to Starship hospital.
Foundation board member Katy Brown said the aim of the centre was to create a "home away from home".
"Transplant children sometimes have to be in the hospital for months and months," she said.
"Our centre would make life heaps easier for their families."