I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
A later custody decision won't automatically impact a custody order. The mother of the other child does not get notified by the court, so unless she went looking for the court order or decided to watch your case to see what happened, she may not even know what the judge decided.
When the judge enters a custody order, that's supposed to include findings of fact, where he explains what it is about the case that impacted the decision. A judge who orders supervised visitation will usually spell out the reasons for doing so in the order - this is largely to prevent a situation where the parent who gets supervised visits tries to appeal and say there was no reasons for that decision. So, most likely, if you aren't able to reach an agreement on child custody and the judge winds up making the decision, yes, the court order will give some reasons that supervised visitation is being ordered.
If either parent moves to change custody for your husband's other child, the fact that the father has supervised visitation for another child could be brought before the judge, and it could play into the judge's decision for that child. It's up to the other parent to decide whether to enter the information - the judge won't go looking for orders from another case, and except in very small towns, it's usually not the same judge. How much effect it has depends on the specific facts of the cases, including when the change is sought and the relationship he has with the older child.
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