NPCs can't damage each other with melee when they're in same faction but have relationship override.

[Gazyi]

https://github.com/ReactiveDrop/reactivedrop_public_src/blob/reactivedrop_beta/src/game/shared/swarm/asw_trace_filter_melee.cpp#L97 There's no way to change NPC faction via VScript or entity input. Relationship check is lower than faction one, so it's ignored. e.g. Antlions and drones that have relationship override will try to damage each other, but fail because they're both from FACTION_ALIENS.