To bulk upload Customers with multiple shipping address in web, please follow below mentioned steps:
Step 1: Go to Customer section and click on Import under Actions.
Step 2: Now, click on Download Customer Template.
Step 3: In Excel sheet, Now add multiple shipping addresses for the same customer by simply adding additional rows with identical customer details and different shipping addresses and save the file.
There’s no limit to how many you can add.
Step 4: Now, upload the file back, at Upload Customers File here.