The Beverly Hills, 90210 star took to social media to show their kids are spending time with another mom-figure while the Transformers actress continues her raunchy, PDA-filled parade with Machine Gun Kelly.
Green has been dating Sharna Burgess for eight months but just made their relationship public in January.
Posting a fun photo showing Burgess smiling in the pool with his children -- Noah, 8, Bodhi, 7, and Journey, 4 -- surrounding her, it appears his sons with Fox are already attached to the blonde beauty.
On Saturday, Green showed his girlfriend and kids soaking up the sun at his lavish Malibu home.
"Pool days :) ❤️," he captioned the shot. "The best days ❤️," Burgess replied.
Green's fans immediately lost it over the photo and showed the family without Fox some love.
"Awesome they have an amazing loving woman to support them and be there for them. So awesome to see you and your family happy," one person commented. "Biggest upgrade ever Brian 👏," shared another.
Green's major dad flex comes just days after his estranged wife grabbed her rocker boyfriend's junk on the red carpet.
Photographers were shocked by the couple's racy display at the Billboard Music Awards last weekend but when the cameras weren't looking Fox and MGK didn't appear happy with one another.
Not knowing she was being recorded, an agitated Fox hurled the f-bomb in her rapper boyfriend's direction.
While MGk has also met Green and Fox's kids, the Jennifer's Body star has accused her ex of "using" their children to make her look like a bad mom.
In October, she blasted her estranged husband on social media for posting a Halloween picture with their son Journey.
"Why does Journey have to be in this picture?" she commented on the post. "It's not hard to crop them out. Or choose photos that they aren't in. I had a great Halloween with them yesterday, and yet notice how absent they are from my social media."
She ended her rant with one last dig.
"Congratulations, you truly are a remarkable human," she wrote. "Why do you need the internet to echo back to you what should be inexhaustibly evident in the way your children love you?"
Fox filed for divorce one month later after 10 years of marriage.