Combatant removal after battle with auto join setting

Im using a turn based battle system in a 3d dungeon crawler type game. Right now I have spider combatants set up to roam the room and on contact the battle starts. If you are pincer attacked from multiple sides you will fight a battle with the extra combatants. The picture below shows a spider combatant on one side of me. There is also another one behind the player character.



The auto join feature works perfectly and when ambushed by both sides I get the following battle with two combatants:



However after the battle finishes. Only one of the combatants is removed from the field. The other combatant remains active and can trigger another battle, this time with only the single combatant.




So my question is: Is there an easy way to remove both combatants from the field after the battle is finished? Im certain its possible but I want to see if there is an easy method to implement this feature before I go about my own ideas.

For more information: I am using multiple combatant spawners on the field with the "remember combatants" feature checked (each spawner has a different ID). They respawn the monsters after 100 seconds

Thanks for any help you can provide!