Great thread, thank you all! DS is 6. When he was 4, we started a story about a young prince who's father is sick. We would both tell parts of the story. It didn't always pertain to XAH's drinking, but I would use it to bring up and talk about what was going on. DS has recently stopped wanting to tell or hear the story. He is, however, doing well talking and playing with his counselor.
Every once in a while, DS wants to read the story "The Brown Bottle" which is a very good book for little ones to explain how alcoholism changes a person, IMO.