Robin Hood

We have renamed Ryan.
From this day forth he shall be known as Robin Hood!
It is well documented that Ryan, I mean Robin is our sneaky kid! I've known for a while that money often disappears. This week I had two fifty cent pieces on the kitchen bench to make up the ten bucks I need for netball each week. When I came out of the shower I noticed that the boys and taken their lunch boxes and the dollar had disappeared. When asked where it had gone Ryan, I mean Robin fessed up! When he was told to return it he only came back with one fifty cent piece. He was asked to go get the other one! I was then informed that he had put it in Matthew's bag!!!
How do you  discipline a kid that is so kind and considerate??????