It's a 2D engine so it's not that simple, but can probably be achieved in a similar manner to what I just provided you with inside of your other thread about preventing the character from walking if the player clicks too close to the character.
Long story short, you listen out for when chasing character enters a specified radius & then you either make them stop or update their path. The latter will be fairly complicated though.
P.S: you should actually be able to use the chase action section where you can set some actions to do if chasing character enters leader characters specified radius.
