How to tell if an part is a parent of another part?

What you're trying to do can be achieved the same way by checking if the part is a child of the model. Here is how you can check if the part is a child of the model,

if not game.Workspace:WaitForChild("Model"):FindFirstChild("Part") then
    print("Part's parent is not Model")
else
    print("Part's parent is model")
end

If I'm being honest I don't think this is the answer to your question. I have no clue what you're trying to do. The point is I tried. Good luck.