China resident Visa expires March 2015 Leaving for US Chirstmas?

My 2 children are getting new US Passports but the old expired passport has their China residency permit good until March 2015. Our family is leaving for Christmas to go back to US. Can I take their old passports to show the China residency permit to come back to Shanghai to our home? Or do I need at least over 6 months left on this visit?