Is your feature request related to a problem? Please describe.
I'm make the NPC following with data syntax, like: /data set entity ObjectiveData.ObjectiveDataSet[2] playername.
The main issue is, removing or change to another nickname, don't make NPC stop following

(I'm missing something?)
Well, i notice now at the end of data pack have a flag "HasPlayerTarget" zzzzzzz

Describe the solution you'd like
Should be a /easynpc kinda like command to start following or changing some settings....
Then i can easily on dialog->action-> /easynpc entity follow....

Thanks for the feedback.
To make sure that the NPC affects the performance as less as possible the NBT objective data are only reloaded in specific scenarios like:

• Targeted objective related entity logged in / out
• Objectives are update over the function addOrUpdateCustomObjective
• NPCs is respawned

I think the easiest option is an specific command for follow / unfollow.
Let me know if there are any other kinds of commands which could be handy to have.