This is a great teaser.
I did it on 5th attempt.
Here are the rules since the website is in chinese. The big blue circle starts the test. Everybody has to cross the river. The following rules apply:
Only 2 persons on the raft at a time.
The father cannot stay with any of the daughters without the mother's presence.
The mother cannot stay with any of the sons without their father's presence.
The thief (stripe shirt) cannot stay alone with any of the family members.
Only the mother, the father and the policeman know how to operate the raft.
To move the people click on them.
To move the raft click on the red balls, at the top of the posts.
Note: please be patient as the game takes time to load for the first time.
Have a go here:-