As much as Bindi Irwin is excited to make her beloved mum Terri a grandmother, sources say the pregnant 22-year-old is starting to realise that baby makes five in their house – and it's not big enough for all of them.
The Irwins – including Bindi's husband Chandler, 23, and brother Robert, 16 – live in the family homestead within the grounds of Australia Zoo on the Sunshine Coast in Queensland.
"None of them can really bear to leave because it's Steve's home," says a source.
"But Bindi is starting to realise she needs to do the right thing by her growing family.
"She plans to talk to her mum about the next step, and as usual, Bindi has an idea. She wants to build a granny flat on the zoo grounds for her and Chandler to live in, or for Terri to eventually move to, leaving the main building for herself.
"By the time the new dwelling is built, Bindi predicts Robert will be around 20 and out on his own, so it makes sense."
The source adds: "Bindi would love the main home but it might make sense to keep Terri in there, at least for now."
"She and Chandler think they might split their time between the zoo and America, where he's from, so the granny flat might be enough for them.
"It's no secret Bindi will eventually inherit the family home – indeed, the entire zoo – one day. Either way it's a bittersweet moment for Terri, who's thrilled to have the new addition to her family but knows it means big changes for her."
Bindi announced her pregnancy on Instagram earlier this month, revealing she is still in her first trimester.
"Chandler and I are proud to announce that we're expecting! It's an honour to share this special moment in our lives with you," Bindi told her followers.
"Though I'm still in my first trimester, we really want you to be part of our journey from the beginning of this new life chapter."