Keith Bremner remains in hospital.
O'Donnell and Tuwhangai's only child, daughter Jo, is among the devastated mourners.
Speaking on her behalf, the whanau's spokesman said she was holding up as best she could.
Her faith was helping her stay strong, he said.
"I'm surprised at her resilience and strength in the face of what can only be a devastating experience.
"I think it is her faith that has kept her resolute and the support of her husband and friends and family. It can only be faith - it's beyond my [understanding] how she can hold it together.''
The couple's tangi today follows a memorial service held for Clare Bremner yesterday, to which about 200 people turned out.
Members of the O'Donnell and Tuwhangai whanau were also present and passed on their condolences to the Bremner family.
They were calling for calm and peace during this time, the spokesman said.
"One of the things that was stressed that despite their grief - and it is a deep-seated grief - that they have extended the hand of grace to the Bremners; knowing that they're also going through extremely tough times.
"It's a time for calm and unity among our communities, for the community to be calm and to come together.''