this is unsolvable. the 2 sets of children that can't travel with the adults and the police criminal pair that must be together make too many dependencies. is this a joke?
The criminal people don't need to stay together, the thief can stay behind as long as she is alone. You can hence use the policeman to ferry a son/daughter. The next challenge is if you go from there and ferry one side of the family across, eventually the boat will be on the wrong side - so you need to make a little tedious shuttling/shuffling session to make sure the policeman/thief duo actually waits on the opposite side. From there, it's pretty straight forward again.
I'd say those are the only two critical sections, the rest should follow automatically.
I'd say those are the only two critical sections, the rest should follow automatically.