Thats true, the collission polygons of the box keeps things inside the layout. That was a very bad suggestion.
I dont know if this 'collission' is supposed the act a 'physics collision', i suppose not.
Then i dont see a problem.
Give the player parts an identification instance variable, say 'id'.
Player instance variable 'id' = bristle.
On (player) overlapping (enemy)
............ do stuff