Lawyer sign is must in each and every process in civil suit

I have Civil suit in court - I am Plaintiff. Appointed a lawyer too. There was third party application allowed by the court to add as a defendant. So I made application to the court to allow me for amendment in the plaint. Court allowed but to add defendant name in the main plaint by red pen, but it is told me that (by Clark) only with appointed lawyers sign that change will be done in main plaint. And hence until my lawyer will sign there is no further action will be take like notice to that defendant. so my question is Appointed lawyer sign is must? Practice or Provision? plantiff sign no?