"There are truly no words to explain the tremendous loss that Tammy's unexpected death brings."
Nathan-Belk's mother Tania told Stuff she was their "ray of sunshine".
"It's a huge, huge loss for us, she was our ray of sunshine, always there for us and we were always there for her."
The initial post mortem listed her cause of death as being due to ruptured acute appendicitis, Stuff reported.
Her health had "deteriorated rapidly" on the day of her death, and after an ambulance was called she had died on her way into the hospital, Belk told Stuff.
Afa said the Givealittle page had been established to provide financial help with the funeral expenses as well as the "burgeoning expenses" of raising four tamariki without their beloved māmā.
"It is our hope that the funds/koha raised from this page will bring some measure of financial relief during and immediately after this time of great sorrow to the whānau," she said.