Honestly if I can just find out where to look for it that would help too, been trying to find it via hex editor but so far nothing has worked. I am trying to add custom monster sprites that have white names and can't be clicked like normal mobs.
This is how mercenaries, pets and homunculus work. The problem is there used to be a patch for this but it doesn't work on clients later than 2017, some kind of LUA error. I don't even need the full breadth of that patch just to extend the ID's from ~6052 to 7000.