Kevin Federline has vowed not to let Britney Spears' erratic behaviour affect the welfare of their two young sons - by becoming the perfect father. Troubled Spears lost her visitation rights to Sean Preston, two, and Jayden James, one, following an apparent breakdown at her home on 3 January (08), after she refused to hand her youngest son back to her ex-husband's minder at the end of a visitation term. But dancer Federline is determined to do his best to ensure the boys remain happy and healthy, despite not being able to spend time with their mum. His lawyer, Mark Vincent Kaplan, tells People.com, "Kevin's not indifferent to how difficult it has to be on their mother (Spears) and on the kids. It's a sad situation. "(Kevin) is committed to trying to fill any void by him being there at all times for them in any way. He can't replace their mother in their life but he is going to try to minimize the hardship."