Simple Modification to Divorce Decree in Tennessee?

[why me]

My ex husband and father of my 2 children and I get along great. We've been divorced for 5 years and basically have forgotten all about our final decree. We basically have settled into our own terms with what works for our children and things couldn't be better. When we first divorced, he carried the health insurance on our children and it was written in our final decree that he would continue to carry the health insurance for our kids. Well, about 4 years ago, his health insurance skyrocketed and since I had excellent insurance and the kids live with me, there was no problem in adding them. Well, recently, I've been told the company I work for will be conducting some sort of verification of dependents. The rumor is that if you are divorced and have to produce a final decree and it states that the ex is to provide the health insurance, then they will kick my children off the plan because they consider it to be against company policy if the children are supposed to get insurance somewhere else first. I need to get the decree modified to state that either of us can carry the health insurance but all the attorneys I've contacted want to charge a fortune and we simply don't have it to spend or split. I can't afford for my children to be forced off my health insurance. Can I modify this decree myself for less money? I feel like I'm being punished and wouldn't even have to do this under normal circumstances.