How to make a bone follow a part while being parented to another part?

So I'm trying to make a "morph" type of thing using the new skinned meshparts update. I am trying to make a bone copy the same movements as another part. By the way, I don't want to make an animation as this is meant to work with all roblox animation packs.

Here is some code:

local RP = char.Luigi.RootPart
local rBone = RP.root.root_motion

local opHead = nil

while true do
	Swait()
	--head
	local bone = rBone.root_body.ske_body.root_head
	local compare = char["UpperTorso"]
	if opHead == nil then
		opHead = bone.Position
	end
	local rotate = Vector3.new(-(hed.Orientation.x - root.Orientation.x), hed.Orientation.y - root.Orientation.y, hed.Orientation.z - root.Orientation.z) - Vector3.new(compare.Orientation.x - root.Orientation.x, compare.Orientation.y - root.Orientation.y, compare.Orientation.z - root.Orientation.z)
	local pos = Vector3.new(-(hed.Position.x - root.Position.x), hed.Position.y - root.Position.y, hed.Position.z - root.Position.z) - Vector3.new(compare.Position.x - root.Position.x, compare.Position.y - root.Position.y, compare.Position.z - root.Position.z)
	bone.Orientation = rotate
	bone.Position = opHead + pos
end