In a dropdown list, how can I have an address with multiple lines?

To have multi-line text fill a text field based on the choice in a dropdown list, you would use  a backslash-n (\n). Here is an example of this:
Chicago Office|123 Main Street\nChicago, IL 60187\nPhone: 312-555-1212
In the above example, the customer will see "Chicago Office" in the drop down menu. When it is chosen, the following will be populated in the area designated for this information:
123 Main Street
Chicago, IL 60187
Phone: 312-555-1212