“I am getting married in a few months for the second time. I have two sons (8 and 10) and she has a daughter. My children do not live with us but she has her daughter who pays irregular visits to the child’s father. I want her ex to be more consistent or to not be in the picture at all. We sit around waiting for him to decide what he wants to do before we can make any plans. My fiancé cannot seem to see how selfish this is. Please help.”

You will face much bigger hurdles....
Yes. Of course you and your fiancé, together, ought to have a conversation with him about how he may assist in making all of your lives less complicated. Be assured your upcoming marriage will confront you with far more complex situations than this one.