Britney Spears will cancel her tour if Kevin Federline’s lawyers block an agreement letting her take the kids, sources tell TMZ. Brit, K-Fed, and Jamie Spears privately agreed on a plan for the singer to tote the tots. But Federline’s legal team has objected to the idea for reasons that aren’t clear. Brit now has almost half custody. A lawyer for Federline says it looks like they'll work it out.