Ohiogal,
I don't think that my ex is going to try to change custody. I texted him yesterday to please stop asking the one child if he wants to come live with him that its causing the older two to feel left out. His response was then fine, I just won't be around them. I responded that he has visitiation and the kids needed him as their Dad. I even suggested he do some research about how to best deal with children and a divorce, which he just laughed at.
I have really put an effort into keeping the children having a relationship with their dad. I went to the point at Christmas to making sure there were presents from Dad under the tree. I let him know when their activities are etc.
He hasn't had a good relationship with the oldest, almost to the point of abuse. The next one tends to sympathize with the oldest and that she has a good relationship with me, Dad tended to just let me deal with her. The younger two, for the past 2 yrs, Dad has told them they were "part of the settlement" in front of the older two, so you can imagine what that does to their psychs.
All I can do is my best for the kids. I will say that my ex is definately not the man I married. The man I married was severly injured in a motor vehicle accident in Iraq and did not come home, this other man came home in his place. 3 1/2 years later, he filed for divorce.