In Financial Accouting, customers are controlled via the account group.
In this IMG activity, you can assign the partner functions that you defined to these account groups. This means that a partner function on the debit side can only be used for customer masters that have been assigned to these account groups. Choose Partner functions. Then choose Environment -> Acct grp assignment.
You can assign the partner function "ship-to party" to an account group but not the partner function "sold-to party". A customer with this account group cannot assume the partner function "sold-to party" in the sales order.
You find account group control in:
Logistics - General -> Logistics Basic Data: Business Partners -> Customers -> Control.