I am sorry you are going through this struggle with your daughter and grandchild. The stakes are much higher because of the grandchild.
I have been through so much with my alcoholic relative, that I am just about out of hope - and I am glad for myself that I am, because my hope was fueled by denial. I believed lies, refused to see what was happening, lived with my image of him in the past, etc. I prayed and prayed and we (the family) have supported rehab, etc. Nothing has changed.
It's up to him but I want to save myself now.
I wish you and your family the best of luck and would recommend Alanon or Naranon to you, even though I don't resonate with it - it has helped many other people.