This is in my view the easiest way to deal with shipping and billing addresses in Filemaker.
You could use all kinds of fancy tricks with selection buttons and hidden fields. But why make things hard if they can be so simple.
Here is the Filemaker File: https://www.dropbox.com/s/b3j6eitq55y8m8f/Shipping.fmp12?dl=1
And my Udemy page if you want to learn how to make entire Filemaker systems: