How to add custom field in Address Book and use it in the dropdown
Go to WPCargo > Manage Form Fields > Add Form Field
Fill out the fields and select Shipper Information /Receiver Information from in What Section do you want to display? and click the Save setting button to save your field.
Go to WPCargo > Address Book Setting
Choose the newly added field in Select Shipper Address Field Search Value option and save it.
Add address book and fill out the fields included out newly added field Customer ID
Try to add new shipment and check the address book dropdown. The customer id should display in the dropdown
