During the interview, Terri, who shares her kids with the late Steve Irwin, also revealed how Bindi first announced her pregnancy to the family, before sharing the news publicly in August.
"She announced that she and Chandler were expecting on our annual crocodile research trip," Terri said. "So here we are all out in the bush and we'd been all jumping crocs and attaching trackers. We're all sitting around the campfire and she says, 'By the way...' We all picked names. We all laughed and cried."
When ET's Lauren Zima spoke to the Irwins earlier this month, they reflected on the kind of grandfather Steve would've been.
"He would've been a good, good grandpa. Yeah, he really would've been," Bindi said. "I don't think we would've ever seen our daughter. He would've just whisked her away into the zoo and it would've been perfect. But it is so nice that we'll be able to introduce her to her grandfather through all of the documentaries. It's really special."
"I think it's really special that as a family we get to remember him, honor him in absolutely everything that we do and make sure that that legacy never, ever dies no matter what," Robert agreed. "And now with a new little wildlife warrior taking on the charge, he would just be insanely excited. I can't even imagine. It'd be amazing!"
As for Terri, she said her late husband, who died in 2006, would be "over the moon" about his first grandchild.