Which lua file controls my custom npc? (path question)

When I was learning to add customs to a gamemode I basically just copied a bunch of the npc.lua file to directories until it worked. (made sure the original in /addons was gone and no subscription)

I’m having trouble nailing exactly which one it is. I’ve renamed the npc.lua in gamemodename/entities/entities to npc.luabackup and it still spawns the npc so I am assuming that’s not it.

Is it the npc.lua file in the autorun (and which one, server or client)

Also, which changes happen live when I save a .lua file and what require a reload/restart gmod. (I have to restart because usually it hangs FOREVER when I reload)