Configure all desired parental controls for a user then run these commands as root:
To export the parental controls plist:
dscl . -mcxexport /Users/keith -o parental_controls.plist
To import the parental controls plist to another computer or user:
dscl . -mcximport /Users/craig parental_controls.plist
NOTE : If you’re using tab auto completion when running the above commands, it will add a trailing slash “ / “ at the end of the user name. For example: /Users/keith/
You need to remove that trailing slash for the command to work. It will fail if the trailing slash is in the command.