Kevin Federline is hesitating to put his John Hancock on his and Britney's final divorce papers, out of concern for how his estranged missus' penchant for partying, though currently quelled, might affect their kids if it resurfaces.

While the couple since March have shared custody of their two sons, a source tells People that K-Fed "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." (In recent weeks, the freshly rehabbed Spears has been spied revisiting the nightclub scene.) Brit's lawyer declined to comment on her personal life and legal situation.