What's best practice for importing customers for both CX Service and AR

Summary:

What's best practice for importing and managing customer data between AR and CX Service?

Content (please ensure you mask any confidential information):

CX Service uses party for the customer and contacts for creating Service Request, Work Orders, etc.

AR billing uses customer account and account sites for invoicing customer.

Is there any best practice how to design customer structure when Work Orders result into Invoices?

Also, if there is any best practice or white paper on how to import customers, contacts, accounts and addresses from legacy system into AR and CX.

AR uses FBDI template to import customers, accounts, addresses, etc. However, data imported into AR is not exposed to Service.