Civil suit - change of constituted attorney of plaintiff

Hi all,

I have a question. My client is a foreign entity, which is the plaintiff in a civil suit. The constituted attorney of the client who signs all the documents on its behalf and who will be present for examination has changed. Can you tell me what kind of an application can i move to bring the fresh constituted attorney on records? Do i need to amend my plaint for this? 

Thank you.