Can an attorney represent someone in court without...?

Notifying the court by filings that they are in fact representing the client? An attorney was representing my ex husband. I received a notice in December filed by that attorney that he was no longer representing my ex yet he has represented him in the last two child support hearings and never filed anything adding himself back as my exs atty even though the child support attorney told him to. Now that we are going back to court for custody and he has still not been added...will he need to be notified ? Will his attorney's ineptness cause the custody hearing to be delayed until he files something with the court adding himself as my ex's atty?