XIAOBAITU, RADIOLOGY AND ALL XDJM, PLEASE HELP...

Dear All,

I am urgently wondering whether any problems exist if my parents go back to china and come back in two weeks, actually on the day before their visa expeired. I mean if the custom officer will ask why you stayed too short in china, or even reject them to enter? Any body has same experience? What disadvantages if staying in china a just for a couple of days then coming back to the US? Please share and give your suggestions. Thanks a lot!