I've had a problem for a long time, I'm not able to set the parent of a model with all of it's children still inside. It still moves the model but then deletes its children.
Model.Parent = script.Parent.Whatever
Child items should not be deleted, you might be doing it wrong.
Your question wasnt very detailed so I will presume that you want me to make a model.
Model = Instance.new("Model") Model.Parent = THEPARENTNAMEHERE
If you are asking why it removes the children, well, it shouldn't at all to be honest.