Customers data in GOP

we have a scenario where customers can log in as 'GUEST' into the SFCC commerce cloud system and place an order using credit cards. we are creating those customers in Fusion while importing an order from SFCC to Fusion through FBDI. But what I noticed is that since the customer was just created, GOP doesn't have this new customer information, Hence, the default Shipping method and other scheduling-related attributes are not getting updated in the order line during scheduling.

The scenario I have explained is the most common scenario in the retail industry. I would like to under how to handle this scenario without GOP data collection for customers.