How do i get an enemy NPC to attack a different player if 4 are already attacking one player?

Basically. What i want to do is when an enemy npc - we'll call attacker is going for a player. I want it to check if there is other attackers already attacking the player, and if there is 4 already there i want it to go for another player instead.

while sp.Parent~=nil and Humanoid and Humanoid.Parent~=nil and Humanoid.Health>0 and Torso and Head and Torso~=nil and Torso.Parent~=nil do

local _,time=wait(1/3)

humanoids={}

populatehumanoids(game.Workspace.Zulus)

closesttarget=nil

closestdist=sightrange

local creator=sp:FindFirstChild("creator")

for i,h in ipairs(humanoids) do

if h and h.Parent~=nil then

if h.Health>0 and h.Parent.Name~=sp.Name and h.Parent~=sp then

local plr=game.Players:GetPlayerFromCharacter(h.Parent)

if creator==nil or plr==nil or creator.Value~=plr then

local t=h.Parent:FindFirstChild("Torso")

if t~=nil then

local dist=(t.Position-Torso.Position).magnitude

for i,v in pairs (game.Workspace.NPCs:GetChildren()) do

local other = v.Torso

local mag=(other.Position-t.Position).magnitude

if mag<dist then

if i >=4 then

-- dont know what to put here

end

end

end

if dist<closestdist then

closestdist=dist

closesttarget=t

end

end

end

end

end

end

this is what i have so far