"We have some exciting news..... coming 1 March 2021," Grant and Chezzi both captioned the video, which shows their two girls sitting at a table with a toy doll.
"So, we have some news. Our mum is pregnant! And mum's really sick. And she's been resting for days," the girls explain.
When he's not hosting Family Feud or Dancing With The Stars, Grant loves nothing more than spending time on his property in Bathurst in country NSW with his wife Chezzi and two girls.
Despite Grant's busy work schedule, the 42-year-old is determined to be as present as possible.
"My greatest concern is not being able to observe every single waking moment with those growing little monsters," Grant explained to TV WEEK.
"Time is going so fast, and they're evolving so quickly in front of my eyes. I don't want to miss a thing – and as a parent, my greatest paranoia is, 'Am I focusing on work too much?'"
"In the hours we're together, we muck around, jump on the trampoline, play with the dolls' house or run outside with the dog. We ride quad bikes together; we go on little adventures," he said.
"I'm deeply protective of ensuring that we have a balance, because it's not a game you want to get wrong. It's about making that time count."
Becoming a father to Sailor and Scout is Grant's proudest achievement to date.
"They're very funny, cheeky and very compassionate and they've got that right amount of spunk about them. I'm totally besotted by them and in love!"
This story originally appeared on our sister site Now To Love.