KEVIN FEDERLINE has yet to discuss his high profile battle with ex-wife Britney Spears with their two young sons - because he doesn't know what to tell them. The pair have been at war since they split in November 2006, and their custody battle over two-year-old Sean Preston and one-year-old Jayden James still wages. Visitation rights were stripped from Spears at the beginning of January (08) following a stand-off with police and paramedics after the singer refused to hand over youngest son to Federline. Prior to that, Spears lost all custody of her sons after failing to adhere to court-ordered medical tests. She now has telephone contact with her kids after a ruling by Los Angeles Commissioner Scott Gordon last week (ends25Jan08), but the former dancer admits he still hasn't found a way to explain the conflict to the young boys. He tells Interview magazine, "No. I don't know (what to say). I haven't crafted something yet."