Puternut,
I can't speak to you from a peer position (as in df'd, divorced w kids) but I can speak to you from being the JW daughter that had a df'd father.
I was a diehart JW and unlike your daughters, was not overly hurt by my parents divorce. My dad was df'd and it was about a year before we had our first visit with him. I had anger and resentment, but we landed up spending a full day with him. He pulled out a smoke, which shocked me initially. But he talked to us about how he was, what he was doing - made it fun. I tried in some respects to "spoil" it, but he didn't allow any of my behavior or comments to affect him. Over the years he stayed constant in who he was. He always showed us love and never talked down about mom or the religion. I remember once I said something negative about mom to him and he told me to never talk bad about my mother (in a rarely heard harsh tone). It impressed me, because she never held back from dissin' him.
I love my dad, and I'm "out"... unfortunately, I don't have him anymore (too long and too sad a story)... but I can give you this advice:
Love your daughters unconditionally. Without condition. Tell them that. It will seem funny at first and they may not accept it as love (after all, God loves conditionally) - but it will stick in their minds and they will love you the same way.
Do not talk bad about their mother or allow them to in your presence. Trust me - this will impress them with your love.
I would recommend not talking bad or adding doubts about the Society. You do not want to be viewed as a "spiritual endangerment". If your daughters bring up points, encourage it or affirm their thoughts, but do not start it. Just be there to support their thinking. That way either way (they stay JWs or leave) you can have a relationship with them.
From your previous posts it sounds like you are in the first stages of re-establishing your relationship with your daughters. Be patient and hard-as-it-may-be don't push it. It will take time, just make good use of the time you get with them.
Anyhow, this is just my experience of what worked for me from a daughter's point of view. I wish you all the best and I'm so sorry for your situation. It will work out in the end.