When I tried to apply logic to my ex's behavior, it got me nowhere and I always just ended up more frustrated and confused than before. He rants and raves about me keeping our son from him, but he was the one who got his phone shut off so he could drink the money, he's the one who only calls about once every six weeks. That call is never to ask about our son or speak to him, it's to bluster about some grandiose plan he has to come visit and pick a fight and threaten me if I don't agree to all of his ridiculous demands and arrangements on the spot. I've gotten half a dozen of those calls since I left. He has yet to come visit once.
There is no rhyme or reason to someone's behavior when they are controlled by a drug. Trying to look at things through our sober perspective just makes it more confusing.
This might be a good time to have an honest talk with your daughters about addiction. Not to badmouth him, but to bring it out in the open and let them discuss their feelings honestly and in a safe environment.
"Dad loves you, but he's sick and making bad choices. We didn't cause it, we can't cure it and we can't control it."
I forget their ages. If they're teens or even tweens, they would be old enough for Alateen meetings. Meeting other kids who have been in similar situations might be helpful to them.