Meanwhile, 17-year-old Robert celebrated his parents' union with a silly photo of them. In the pic, Steve is smiling as he sits in a wheelbarrow with crutches, while Terri happily pushes her injured husband.
"Happy anniversary, Mum and Dad," Robert wrote. "This is my favourite photo ever."
"He would've been a good, good grandpa. Yeah, he really would've been," Bindi told ET in February. "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."
Terri noted that her late husband would've been "over the moon" about becoming a grandpa, and sentiment that Robert agreed with.
"I think it's really special that as a family we get to remember him, honor him in absolutely everything that we do," Robert said. "And make sure that that legacy never, ever dies no matter what. 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!"