I don’t let my parents call me after 6pm so they can’t drink and drive

My parents are both alcoholics and don’t see anything wrong with driving drunk. They’ll even do it with my younger siblings in the car (ages 9 and 10). I’m 19 years old now and I moved away at 18 to go to college. I don’t answer calls or texts from them after 6pm. If I’m not able to prevent my siblings from being in the car with drunk parents, I at least don’t want to be the reason they get in the car. It’s definitely helped and now they don’t call/text until the next morning but it’s just so crazy that I even have to do that.