"I couldn't have asked for a better dad to raise me. He's a wonderful dad and we're had a very privileged life, and that's all thanks to him."
Miss Flay said her father took her and her siblings on family holidays overseas, including a trip to Hawaii and the United States on her 18th birthday, and paid for them to get into good schools.
Her childhood was filled with fond memories, laughter and happiness, she said.
Raising her and her twin, along with his own daughter, couldn't have been an easy task for him to do, Miss Flay said.
"I think it's a huge ask for someone to raise a child who is not their own. Men who do that, I think, have such big hearts. Hearts that are twice as big as some of the biological fathers out there."
Miss Flay said Father's Day was an important day in the calendar for her family, and was a time where they recognised the positive contribution her father had had on their lives.
"For us Father's Day is about thanking him, and all the other stepfathers out there who have raised other people's children. It takes a special man to do that, so thank you."
Rotorua Parents Centre president Jo McQueen-Watton said Father's Day was not just about celebrating fathers but all male role models in people's lives.
"We always encourage any male role model, whether that's a stepfather, biological father, grandfather or uncle or whoever, to come [to the parents centre]." Having a male role model was hugely important and was something to be celebrated, she said.