Jackie Chan playing Po's father in the Chinese dubs....sigh...

This doesn't apply to the Taiwanese dub but in the Cantonese and Mainland China dubs of KFP3, Jackie Chan not only serves as the voice of Monkey (Jay Chou does Monkey in the China and Taiwan dubs) but he is also the voice of Li Shan (Po's father). Been trying to find any referenced articles on that but why?! Why go thru all that trouble of switching Monkey's voice just to give Jackie Chan a significantly bigger role?!