Best way to set up an AI when one NPC will move and the other won't ?


The title actually sums up my problem. What I am trying to do so far :

Go to the NPC, interact with him and a dialogue option opens up. I click on “MoveTo”, I interact again on the floor and the NPC moves to that objective. But the other NPC is also moving while I was not talking to him.
For now, the AI is continuously trying to get to the “Objective” so as long as I am not giving it a new location, the NPC won’t move.

I can’t imagine you have to have as many AI as you have NPC. I am not asking for a full blueprint screen, but perhaps for an algorithm with some key nodes (for instance, the RunBehaviorTree is mandatory but you can just asign a AI and not specify a BP_NPC, which I would like to do).
Or even a Youtube video or a tutorial showing me how to approach that problem.