As I recall, the Registration of a foreign judgement (TX --- > IL) was primarily an administrative process from county clerk to county clerk. I believe there may have been a cite to statues justifying jurisdiction along with a judge's signature or at least an officer of the court (ie Tx atty). Pertinant infomation of each child of the marriage like full name, date and place of birth and perhaps SSN had to be recorded. Possibly the same for both parents. A signed and dated copy of the Order was to be attached. A court clerk should be able to assist and expedite this process. Of course these documents are a matter of public record.