Shooting anywhere within 30m of a Class-D (regardless of friendly fire) will transfer damage to the Class-D instead to encourage KOS.
Additionally, you can change the distance to instead being zone-wide or facility-wide.
Config:
improvement: Distance
# Different improvement types:
# Distance: uses the below distance config
# Zone: transfers damage to any dboy in the same zone
# Facility: transfers damage to any dboy regardless of position
max_distance: 30
allow_friendly_fire: true