I don't have kids so have never been in this situation but I am an ACOA. What I would suggest is to make sure YOU are modeling strong, unapologetic behavior for them. As an ACOA I have had to do conscious work related to this. I distinctly remember at age 17, being told by my BF that I say I'm sorry too much. What I now do, especially at work, is never apologize for anything that is out of my control. Of course I am still polite so for things like accidentally stepping on someone's foot I still will say I'm sorry.
Also, when you're a kid of an alcoholic, you just don't get enough attention. So make sure to spend quality time together and be sensitive about giving them equal attention and equal things. If you give one a gift or buy something for her, make sure to give or buy something similar to the other. Sounds like a pain but they are special kids having had to endure what they've endured, and what they continue to have to endure with visitations with their dad.
Thanks so much for paying attention to your daughters' needs and trying to compensate for the fact that they have an alcoholic parent.