Unreal Chasing NPC project

I’m a complete noob, and midway to make this project: a NPC (called Police) that chases cylinders (called thieves), the Police is supposed to patrol a vigilance area until a thief enters said area, in which case the Police will start chasing the Thief until the Thief has left the vigilance area, as soon as thief enters vigilance area Police should start chasing and as soon as it leaves said area Police will resume the patrol, if 2 or more Thieves enter vigilance area, Police should keep track of that, and start chasing first the one that entered the area early, if the one that was chasing left the area, Police will check if any other thieves remain in vigilance area and will start chasing them in order of entrance.

I mostly got the part to patrol and chase good, but I’m trying to make it instantly swap between chase and patrol when thieves enter of leave the area, and I’ve made no progress on tracking and chasing multiple targets

I would gladly accept any help to do this, or if there is already a tutorial to make it, a link to it.