Trying to add NumberSequenceKeypoints values, but it doesnt seem do anything?

What i need to do is exploding particle size changes depending on the npc size.
All i did was storing the NumberSequenceKeypoints from the particle size in table then set that to the particle size, but then i dont see anything change.

Code

local particle = script.Parent.Attachment

function AddValueParticle(inst,add)
	local oldkeys = {}
	for i,v in pairs(inst.Keypoints) do
		oldkeys[i] = NumberSequenceKeypoint.new(v.Time,v.Value + add,v.Envelope)
	end
	inst = NumberSequence.new(oldkeys)
end

AddValueParticle(particle.Explode1.Size,5)
AddValueParticle(particle.Explode2.Size,5)
AddValueParticle(particle.Explode3.Size,5)
AddValueParticle(particle.Explode4.Size,5)

You need to wait before running the function. Add a task.wait(1) before calling it.

Still nope. The size still stay the same
image