Based on what I've seen, those who wait to start drinking until well into adulthood have brains that are MUCH more resistant to alcoholism.
The implication for you, then, is that if you can't get your sister to just join you in being a non-drinker, then at least persuade her to procrastinate her drinking as many years as possible and use the language-learning analogy if it helps: the LAST thing you want to do is become a "native drinker". You want it to be something always a little foreign and unnatural to your brain so you can push it away entirely should you ever choose to do so.
Again, this might be of no use to you in your personal situation (and sorry I can't be more useful), but if there's any way you can get her to wait until after college/university age, she won't be completely safe (no drinker is), but she will have MUCH more power than she has now.
Unfortunately too late. My sister has had her first drink a year or so ago. She was 14 iirc. I had mine at 11 - 12.
We can shun alcohol. I have a bottle of Jaeger in the fridge untouched. I got it last Christmas.
In effect, being stupid with it when I was a kid made me realise I have a point where it isn't pleasant at all. It also made me realise that I hate the idea of me under the influence - I hate feeling like a fucking idiot.
That plus the damage it has done through other means has left me a non-drinker. If alcohol became a class A substance tomorrow and the day after consuming it was punishable by summary death, I would not care (except maybe about a right wing govt). I wouldn't give a shit about losing booze.
I also have young children. If I won't jump in a car after 1 drink, how can I look after my kids? What if one wakes up?
An interesting read, and recommended for one very talented person's view on alcoholism.
[1] - https://librivox.org/john-barleycorn-or-alcoholic-memoirs-by...
The drink has ruined my relationship with them.
When I was a teenager, me and my sister suffered from psychosis. They blamed their drinking on that. When we got better, they continued and found a different scapegoat.
My sister is going through children's mental health services. My parents don't seem to understand that wrestling tablets from my mother attempting suicide is traumatic for a child. This is really messing up my sister.
When I spoke to my dad about my sister's problems, his response was "I'm not giving up my life for some 15 year old"
Over the years, I'd get nasty text messages. Anything from long essays on why my birthday gift wasn't adequate to how my choice of partner isn't adequate (my partner demands that the kids don't have cordial - my mother disagrees). Years of that plus childhood has made me feel inadequate.
Alcoholism doesn't just screw over the drinker but the family too. Sometimes it's not just the pain of watching them fall.