How to position a model relative to its parent?

I've got a model made up of several nested models in ReplicatedStorage. I clone this into my workspace at a desired location, however I don't clone any of the submodels, because the player unlocks them through various upgrades. Later, once they acquire the upgrade, I want to then clone only the upgrade component into the world and place it at the proper location relative to the rest of the model.

Say for example I have this structure in ReplicatedStorage.

Foo

|_ Upgrade1 (Model)

|_ Upgrade2 (Model)

|_ PrimaryPart (Part)

This is already laid out perfectly, so if I were to clone the entire thing into my world it would look fine. However I only clone

Foo

|_ PrimaryPart

I want to add in Upgrade1 after the fact and have it appear in the proper location relative to the rest of the model, and then later on the same for Upgrade2.

How can I do this?

If I understand correctly, this is the way most tycoons work. Parent the whole model to workspace and Parent the children to nil. Parent them back to the workspace when you upgrade and it will put them back to where they need to be.

I found an answer to my own question:

local function orientRelativeTo(referenceChild, referenceParent, workspaceChild, workspaceParent)
        -- referenceParent and referenceChild are objects that are stored in a model in ReplicatedStorage that are already positioned the way I want.
        -- workspaceParent has already been cloned into the world from referenceParent and placed in an arbitrary CFrame.
        -- The below code will figure out how to orient workspaceChild relative to workspaceParent so that it looks the same as it does in my reference model.
	
	local parentToChild = referenceParent.PrimaryPart.CFrame:ToObjectSpace(referenceChild.PrimaryPart.CFrame)
	
	workspaceChild:SetPrimaryPartCFrame(workspaceParent.PrimaryPart.CFrame * parentToChild)
end