Sometimes we need to develop one-lines before the model is set up so we are unable to place 3d elements in the model itself, but we will develop one-lines in drafting views. This would be a great option to use the one-line families to create the one-lines and then either automatically link the elements based on a parameter such as panel name or to be able to go in and link the elements in the one line to the 3d elements once they are modeled.