[1.7.10] Changing other players names client side?

[TealNerd]

I want to make a client side mod that allows you to set nicknames for other players. You open a gui, type in the account name and nickname, click ok, and it saves the data to a text file. Is there an event where I can access the player's nametags and modify them?

[TealNerd]

That event isn't working, I'm trying to do

 

event.displayname = event.displayname + ", Nickname: " + Nickname.getNickname(event.displayname);

 

and when I install the mod and join a server none of the nicknames are displaying

[TealNerd]

Where do I call refreshDisplayName()? Calling it within the event is bad and when i call it outside the event nothingh appens