Britney Spears was thisclose to putting the final nail in the coffin that was her marriage to Kevin Federline, but now Kev is resisting signing the final divorce papers. K-Fed says that, due to Britney's recent party girl behavior, he may want to revise their custody agreement before settling. Under an agreement the couple reached in March, Britney and Kev planned to continue their interim arrangement of joint legal and physical custody of Sean and Jayden. "Britney's attorneys are anxious to see Kevin sign off on a divorce," a source told PEOPLE. "But Kevin and his lawyer Mark Vincent Kaplan are dragging their heels out of concern over reports of Britney's post-rehab partying." Kevin's peeps also "wants to make sure that the divorce document makes it simple enough for Kevin to downsize Britney's access to her kids the next time her behavior troubles him." Can you say "I suddenly think I need a tad more cash?"