My own experience with my drinking sib is that he doesn't want to stop drinking.
Never has.
He had a period of forced sobriety when we wouldn't let him live with my mother, and he lived in a sober house.
It was sad, in that during this time he looked and seemed healthy for the first time in years.
So much so that we agreed to let him move back in with mom, which is what she wanted, in a big way.
Big mistake.
Within a year he was drinking again.
Now it's game on, practically 24/7.
He resents me and my other sib as well. Not sure why.
As a result, I speak to him as little as possible.
I have wished we had a better relationship, but I know that isn't going to happen, now, and probably not ever.
It is what it is.
I too can't see why you should make amends to your sister, nor do I feel you can help someone who doesn't want the help.
Maybe someday.