In fact, the 10-year-old had the most adorable reaction to learning that there's a baby on the way for their blended family, revealed Josh, who is currently expecting his first child with wife Audra Mari.
"He's like, 'Wait, now, am I going to be—You're still going to love me, though, too, right?'" the Shotgun Wedding star told Parade in an interview published Sept. 21. "I was like, 'Of course I'm going to still going to love you.' And he's like, 'I'm still going to be your firstborn son, though, right?' I'm like, 'Yeah, you're still the firstborn son!'"
Describing Axl as a "really sweet kid," the 50-year-old added that his son "loves babies."
"And he's really good with younger kids," Josh said. "So I think he's going to be a great older brother."
It's a sentiment shared by Fergie, who was married to Josh for eight years before their 2017 breakup. After all, the Black Eyed Peas alum had nothing but well wishes after the Las Vegas actor announced that Audra, 29, is pregnant.
"I am truly happy for you guys," Fergie commented on the couple's joint Instagram Sept. 11 post. "Axl can't wait to be a big brother."
And, according to Josh, co-parenting with the-48-year-old has never been better these days. "Fergie is an amazing woman," he raved during an appearance on SiriusXM's The Jess Cagle Show earlier this month. "And she's taken Audra in. And it could be much worse. That's the thing is you never know how these things are gonna go."
One big reason behind their successful dynamic? "Because she's such a kindhearted person," Josh shared of Fergie. "I can't believe how excited she is for us."
He added, "Like I said, it could be a lot worse. And I've seen it. I've lived it. And thankfully we have a really civil situation."
Keep reading to see Josh and Fergie's family moments with Axl through the years.