Devoted dad is determined to rebuild his relationship with his youngest children, twins and , while he still has legal visitation rights with the almost-17-year-olds, sources tell The National ENQUIRER.

An insider says the Fight Club star, 61, is resolved to win Vivienne and Knox’s trust again and repair the damage caused by his separation and divorce from their mom, , 49.

All the couple’s other children, , 23, , 21, Zahara, 20, and Shiloh, 18, are adults and aren’t legally obligated to spend time with him, and in fact, refuse to even acknowledge him and have dropped the “Pitt” from their names.

“But Brad has one more year where Vivienne and Knox are mandated to spend time with him” per his custody agreement with Angelina, the insider says. So when the twins turn 17 on July 12, Brad will be sending gifts and making every effort to celebrate with them in person.

“It’s a pivotal moment. He knows time is running out and this may be his last real chance to rebuild a connection before they graduate and head off to college and their own lives, so he’s going to go all out to get as much one- on-one time with them as he can,” the insider says.

“He’s aiming to be in L.A. way more so he can focus on them.”

As ENQUIRER readers know, Brad’s relationship with the six children he shares with Angelina has been strained since the Maleficent star slapped him with divorce papers in 2016 following an altercation on board a private jet that involved their then-15-year-old son, Maddox. Brad has since accused Angie of parental alienation, says an insider.

His visits with the kids are so precious to him, “he can’t imagine that the kids don’t feel something,” the insider says.

“You just have to see Brad with them to see how much he cares — he lights up when he looks at them,” the source adds. “It’s been hard to arrange a lot of visits this past year because he’s been traveling so much for work, but he’s saying this coming year will be different.

“He won’t give up and will never write them off,” insists the insider.