[Excaliber]

Whew, that was tough. I did it several times and was not sure how until I wrote it down very carefully.
cop+prisn>
cop<
cop+boy>
cop+prisn<
dad+boy>
dad<
dad+mom>
mom<
cop+prisn> (key move right here)!
dad<
dad+mom>
mom<
mom+girl>
cop+prisn<
cop+girl>
cop
cop+prisn

Even WITH the solution it is very easy to screw it up. Good luck with that.

Ernie