How do you get a wedding in Canada between a Canadian and Chinese national recognized in China?

Sandra, if they want to make their marriage legal in PRC, then they should register their marriage at local Civil Affairs Bureau. I suggest that they register before they go on the procedure in Canada. If they register their marriage certificate in Canada first, then they will have trouble registering their marriage in PRC.

The required document for your son:
1. his passport with valid entry permit.
2. single certificate. It should be notarized and certified by your Ministry of Foreign Affairs. Then he needs to have it authenticated by Chinese embassy/consulate. After he enters PRC, he is required to notarize the authenticated marriage certificate and translate it into Chinese version.

Your daughter in law is required to submit her Chinese ID card and Household Registration Book.