Just to make sure its clear what my problem is :
Lets just say there are 3 enemies , enemy1,enemy2,enemy3.
enemy1 does 4 units of damage to the wall per second , enemy2 does 1/sec , enemy3 does 2/sec
now if I use my closest to working method of just using overlap detection with a few pixel of outer boundary added to said enemies , with PickedCount * Enemy.DMG , then the game is just gonna multiply the first attacking enemies damage with how much enemies are currently attacking , so if all three enemies are damaging the wall this would result in 12 dmg/sec , while what I need is 4+1+2 = 7dmg/sec