Sandra Bullock's camp is making sure she has a very happy 46th birthday on Monday by putting the kibosh on troubling tabloid talk that she's considering giving newly minted ex-husband Jesse James a second chance. The reunion rumors began swirling in earnest last week after the two-timing motorcycle mogul won a custody battle with ex-wife Janine Lindemulder to take their 6-year-old daughter, Sunny, to Austin, Texas, where Sandra has a home base. "The only reason that Sandy gave the green light to Jesse's move to Austin was because she wants to maintain a relationship with his children," a source tells Radar Online (James is also dad to daughter Chandler, 15, and Jesse Jr., 12). "Sandy loves those children but she has absolutely no intention of getting back together with Jesse, ever." The affable Oscar winner, who took a break last week from bonding with ridiculously cute son Louis to meet with director Stephen Daldry ("The Hours," "The Reader") in Austin, "is civil to Jesse for the sake of the children. That is it," relays the insider. "If there were no children, Sandy would have nothing to do with him, period. And he knows that."