Are you in AlAnon? Find a group near you, it's an awesome safe place to get experience strength and hope from others dealing with A family members.
Nothing changes if Nothing changes. As long as your daughter is provided with a safe place to carry on her addiction, there will be no motivation to change. You mention your GD's Dad...is he aware of the situation? He may need to step in, if he's dependable, on behalf of his child.
You didn't Cause the disease of alcoholism, can't Cure it, and can't Control it. You have no power over your daughter's choices. But you do have control over what is acceptable in your life. You can set boundaries.
Keep posting, there is a lot of wisdom on this site.