How do I move multiple parts in the same direction with one script/function?

I am trying to create a sliding door made of multiple parts all moving in the same direction. CSG is not an option in this case.

Now, with all of that in mind, I have a script inside a model. The model contains a button, (named "Button"), the "MainDoor" Part, as well as three other parts called "TopDoor." There is also a BoolValue called "IsClosed" that I am using as a switch to keep the doors open and closed.

How should I convert the below script to include the other parts being moved exactly 6.8 units up along the Y axis, keeping them "attached" to the "MainDoor" part?

Code:

door = script.Parent.MainDoor
open = script.Parent.IsClosed
debounce = true

function MoveDoor()
	if debounce == true and open.Value then
		open.Value = false
			debounce = false
			for i = 1, 68 do
    		door.CFrame = door.CFrame + Vector3.new(0, 0.1, 0)
    		wait()
			end
			debounce = true
		else
	if debounce == true then
		open.Value = true
			debounce = false
			for i = 1, 68 do
    		door.CFrame = door.CFrame + Vector3.new(0, -0.1, 0)
    		wait()
			end
			debounce = true
		end	
	end	
end

debounce = true

script.Parent.Button.ClickDetector.MouseClick:connect(MoveDoor)