Fdh's relationship with his children is what it is. Whether you consider it good or not , they and Fdh have chosen that relationship, They chose to work at it and accomplish just as much or as little of a relationship as it is.

From my own experience of marrying a man with adult children I have found it does no good to think you are going to fix what they and their father do not consider broken. You will end up wasting a lot of energy , time and finances into a lost cause. You will end up finding yourself being the scapegoat when they are told "no" and you will be the blame for many things when the responsibility should be placed on their father.

I was once a foolish new wife that thought I could fix what I considered a not so good relationship between DH and his girls. His version---he loved his children but they were all huge disapointments,just like their mother,open to the public, irresponsible,used him as if he was a bank to drain, and of course he took no responsibility for how they turned out, In the beginning I was stupid enough to believe his version.

I soon found myself in a situation where he would make promises and commitments to them that he was not in a position to fulfill. I was left covering for his promises. He would look like the good guy "DADDY HELPED" and I was the scaoegoat if I said" no" or refused to make it possible {enabled} for him to help.

Be thankful they are in your life as little as possible. Do not make them a topic of conversation but if they come up say nothing negative, The relationship is their problem to solve.

I can see where you are coming from, kind of. My SO has a son living in another state with his mother. BM is very difficult to deal with and we disagree with a lot of her parenting skills. I have ranted and raved about how I can not believe that he is not more passionate about his own blood, but nothing has really changed.
The other day my friend simply told me, "He's ok with being a part time dad, and letting BM have the control. It's up to you to decide if you're willing to be with a man who will do that with his own children, and potentially the children you have together in the future".
That was an eye-opener for me. And a true statement.
I think it would be different for us, for a myriad of reasons.. But that's a whole 'nother post.

I have the same situation with my SO. SD21 is pregnant right now we think she is separated from her husband. She moved from east coast (where her husband is) back to CA because she missed her BM and SD 12 too much. Now she isn't speaking to he BM and is living with SO's brother. She has lied and lied to SO over so many things he has tried to have a relationship with her but then it's drama and lies again. So now he has her at arms length. I feel bad that she has nowhere to live but SO is staying strong. She keeps sending heartstring messages to his phone. I miss you dad ,I wish we weren't like strangers, I need you in my life which before this would have sent him running to her side. But I think she finally showed him her true colors. He is done!

I keep bringing up that maybe he should talk to her or go by and see her. He said no that he has his boundaries and that's it. I feel bad for him because I know it hurts him and I couldn't imagine not seeing or speaking to my kids. But I'm staying out of it.

If he wanted a relationship with his kids nothing would stop him. He doesn't want it, and he uses you as an excuse. In doing that in his mind he isn't a lousy father, just a great SO to you.

People think it is a shame when father's don't see their kids, but trust me any parent who cannot be stuffed making an effort to see their kids is no parent at all and the kids are better off without him. The ups and downs of a relationship with a dad that cannot commit are worse than coming to terms with the fact that he is what he is.

For your sake and for the kids sake - leave this alone. You cannot force love or relationships and you may well be involving the children in something they'd be much better off without. If they want him, they will find him, if he wants them, he will find them. This is between him and his kids not you.