I think an intervention needs to include a plan. "Here's what's wrong and here's a solution I think will work". My own son went to counceling and old wounds were opened every week but they never discussed solutions except what he should stop doing. THE most important component in success, in my humble opinion is to start by validating their feelings. Drinking is a coping mechanism. Coping with what? There needs to be validation that their feelings are valid. Then, I think an intervention can proceed to the evidence that it is ineffective coping. I think this makes it feel like less an attack. Just my observation. Not once were my sons reasons and feelings validated.