Brad Pitt has had a great few weeks. Just over a month after gaining joint physical custody of his six children with Angelina Jolie, the actor got to ring in his 55th birthday (Dec. 18) with five of them — oldest Maddox, 17, opted out — during an overnight at his Hollywood Hills home. “[This] was incredibly significant,” a source tells Us, noting that it was the first time the brood had spent the night at their dad’s “since the custody deal was reached.” As part of the November agreement, visits with Maddox, Pax, 15, Zahara, 13, Shiloh, 12, and 10-year-old twins Knox and Vivienne are monitored. That included the overnight. “The visits will continue to be monitored until the therapists agree that it’s no longer needed,” the insider explains.…
