To generate Multi-Site Invoice Statements navigate to the:
Customer > Accounting > Invoice > Multi-Site Invoice tab.
Select All of your Multi-Site Invoices for the customer then Create Invoice Statement (Print or Email).
The Multi-Site Invoice Statement PDF groups the Multi-Site Invoices by Billing Group Name for an organized look and feel to the Statement. If the Multi-Site Invoice is not associated to a Billing Group, then it will appear in the N/A (No Billing Group) section of the Statement.