There are 3 methods to add shipping address, See below

Method 1: While adding new customer

While adding a new customer you will see the option to add a new Shipping Address

Method 2: While creating sale invoice

Under the customer information section, You will see the Shipping Address field, Which is checked by default. Just uncheck it to select another shipping address or to add new shipping address

Method 3: By editing existing customer

Step 1: Go to “Customer / vendor” Menu and click on “Edit” button

Step 2: Scroll down You will see option of Shipping address then click on “Add” button and fill in the shipping details then click on “Save” button