Legal Question in Family Law in Illinois

The decree stands until it is modified. It can only be modified through a petition. Some significant change in the mother's ability to cope would be grounds that would be set forth in the petition. You always have to give a reason why a judge should do something. Modifying an existing order takes stronger reasons because there is always something that happens in court proceedings that did not get into the record. Sometimes it is just a judge's "gut instinct". Judges will almost always defer to the previous judge unless there is a strong reason to do otherwise.

If the non-custodial parent were to get custody there would have to be some kind of change in the non-custodial parent's situation as well. There were reasons that the non-custodial parent got visitation rights only. You would have to show that those reasons/grounds no longer applied. You might succeed in her loosing custody, but that does not necessarily mean that you get it. After reviewing the situation, the judge could put the children in foster care or even up for adoption. The fact you only have visitation rights would, on its face, indicate that there might (have been) be a problem with you having custody. You would be in a stronger position if you had been given joint custody to start with.

Remember, the Law of Unintended Consequences operates in legal matters all the time. You need an attorney who is experienced in custody matters.