Millie Bobby Brown and Jake Bongiovi’s respective families are over the moon after the couple adopted a baby girl — and that includes the child’s proud grandpa, rocker Jon Bon Jovi.

“Jon has always been a hands-on dad so it’s no surprise that he’s completely embracing this new grandpa role,” a source tells Star. “He and [wife] Dorthea are both in heaven. They love babies.”

As Star previously reported, Brown, 21, announced in a statement shared on Instagram on August 21 that she and Bongiovi, 23, had welcomed their first child together via adoption.

The source adds that Brown and Bongiovi — who are “holed up in East Hampton” with his family — are “bonding and soaking up this very special time” with their newest addition.

Plus, the “Livin’ On a Prayer” singer, 63, can’t help but “brag to everyone about what natural parents Jake and Millie are.”

“He’s so proud of them and says he’s blown away by how mature they both are,” the source continues. “Having a baby around again is bringing so much joy. They’re in this beautiful bubble right now.”

Jake Bongiovi and Millie Bobby Brown pose together on the red carpet, with Bongiovi in a black suit and Brown in a pale pink gown decorated with black floral accents.

Jordan Hinton/Image Press Agency / MEGA

The Stranger Things star and Bongiovi have been very open about wanting to adopt in the past — and Brown has previously said that she wanted to be a young mom.

“My mom actually had her first child at 21, and my dad was 19,” she said on the Smartless podcast. “You know, it’s been my thing since before I met Jake.”

However, the source reveals that she and  Bongiovi don’t “plan to stop at just one.”

“They want at least four kids, but it won’t surprise anyone if they have more because they’re both so family-focused,” the source tells Star. “They’re young but they’re both way more mature than the average 20-something, so this just feels right for them.”