New feature for 8.1: Shared number sequences for customers and vendors with copy capability

You can use shared number sequences to assign customer IDs or vendor IDs. Shared number sequences also let you copy customers or vendors from one legal entity to another legal entity but use the same IDs in both legal entities. You can also assign shared number sequences by customer group or vendor group. 

When you copy a customer, the system tries to save the new customer information. Validations are run to verify that the data that was copied is good. You receive an error message for every validation that fails. The error messages explain what information must be updated. The copy of the customer can't be saved until you fix all the validation errors.

For  more information, follow these links:

https://docs.microsoft.com/en-us/dynamics365/unified-operations/financials/accounts-receivable/copy-customer

https://docs.microsoft.com/en-us/dynamics365/unified-operations/financials/accounts-payable/vendor-copy