They get regular updates and photos of Kyrie but were still surprised by how much he had grown.
Riann had no regrets about the whāngai, despite a few teary months.
"In the beginning it was hard for me but I didn't regret it. It was the right thing to do," she told the Herald.
"If you don't know how close our family is you wouldn't understand… We're pretty close."
She said it was "emotionally raw" doing the documentary as it meant they had to articulate intimate thoughts they wouldn't normally talk about every day.
It was challenging explaining whāngai to their three kids aged 3, 6 and 11. But the best part was seeing how delighted Des and Luana and their 15-year-old son Blade were, Riann said.
"Just hearing about how happy they are. That's all we really wanted when we decided to do that."
Whāngai parents Luana and Des Mihaere were still feeling overwhelmed and grateful.
"For us that [the whāngai] has been the greatest decision. Still until today we can't believe they'd do something so awesome," Des told the Herald.
"We're just so grateful to receive this bundle of joy. There are no words we can say to express how grateful we are."
Des said Kyrie didn't sleep very well at the beginning but he's now settled and in a routine. To Kyrie, Luana and Des are mum and dad. They hadn't discussed what Kyrie would call Riann and Tumatauenga but Des thought they were more like a "mumma and papa".
Des said it had bought their whole family closer as they now talk most days.
"We are so grateful for the opportunity to be parents again. I just can't say enough about my sister and her husband for giving us this opportunity.
"He [Kyrie] has really got some attitude about himself. He's a real chatterbox, he'll just respond back with his baby sounds.
"It's been such an awesome journey so far. And I'm sure it will continue."
The families will next get together in September for Kyrie's first birthday when Riann, Tumatauenga and their kids fly over to Brisbane.
Luana said it had gone as smoothly as it could and they were enjoying life as a family of four.
"Since Blade [now 13] was little he always asked for a brother and sister, then it was always a dog.
"Now he says Kyrie needs a dog."