This is difficult but fun... it took me about 45 minutes to figure it out.
The object is to get the whole group across the river while following the following rules:
1. Only the Father, the Mother and the Policeman know how to operate the raft.
2. Only 2 persons on the raft at a time.
3. The father can not stay with any of the daughters without their mother's presence.
4. The mother can not stay with any of the sons without their father's presence.
5. The thief can not stay with any family member if the Policeman is not there.
Cut and paste the following link into your browser and click on the blue dot to start.