How do you move a model using CFrame without adjusting the model's orientation?

I cannot use

Model.PrimaryPart.Position

-because that doesn't bring welded parts with it. I also cannot use

Model:SetPrimaryPartCFrame

-because I need to move the model in a tween. (Unless that's possible- but I don't think so)

So I'm currently using:

--Position I'm moving the part to, (Works great)
local MouseHitRounded = CFrame.new(math.round(Mouse.Hit.Position.X/grid)*grid, math.round(Mouse.Hit.Position.Y/grid)*grid, math.round(Mouse.Hit.Position.Z/grid)*grid)

--Tween itself with CFrame.Angles, (Not so great)
local Tween = TS:Create(placingpart, TweenInfo.new(0.2, Enum.EasingStyle.Quart, Enum.EasingDirection.Out), {CFrame = CFrame.new(MouseHitRounded.X,MouseHitRounded.Y,MouseHitRounded.Z) * CFrame.Angles(0,0,0)})

Tween:Play()
Tween.Completed:Wait()

I've also tried

local Tween = TS:Create(placingpart, TweenInfo.new(0.2, Enum.EasingStyle.Quart, Enum.EasingDirection.Out), {CFrame = CFrame.new(MouseHitRounded.X,MouseHitRounded.Y,MouseHitRounded.Z) * CFrame.Angles(math.rad(placingpart.Orientation.X),
math.rad(placingpart.Orientation.Y),math.rad(placingpart.Orientation.Z)))})
--^^ (All on the same line, ScriptingHelpers was glitching so I had to split it up)

But that creates weird glitches where the part will bounce rotations back and forth.

Because I'm teleporting the part to the player's mouse, the code constantly runs- if that changes anything.

There are numerous threads with this same question that I've looked at, but the threads I've found haven't been under the same conditions. I've been stuck on this for a few days. Any help would be much appreciated. <3

CFrame.new(Vector3.new(0,0,0))

that only does position. not rotation.

i have come with a script a week ago that tweens models, see if this is any use

local ts = game:GetService("TweenService")
local rs = game:GetService("RunService")

function tween(obj, goal, es, ed, time) --uses ts:GetValue to "tween"
	if not obj.PrimaryPart then error("No primarypart, can't proceed") end
	local es = if es ~= nil then es else Enum.EasingStyle["Bounce"]
	local ed = if ed ~= nil then ed else Enum.EasingDirection["In"]

	local start = os.clock()
	local initial = obj.PrimaryPart.CFrame --initial position
	while true do
		rs.Heartbeat:Wait()
		local delta = math.clamp(
			(os.clock() - start)/time,
			0, 1) --gets delta (to use with ts:GetValue())
		if delta == 1 then
			print("finished")
			obj:SetPrimaryPartCFrame(goal)
			return
		end
		obj:SetPrimaryPartCFrame(initial:lerp(goal, ts:GetValue(delta, es, ed)))
	end
end

about the "keeping orientation" i think you could just use a constant orientation vector3