Go to Settings > Addons and turn on Subsidiaries.
This enables you to have multiple billing addresses which you can use on Invoices and Proposals.
Creating a new subsidiary
Once you have activated Subsidiaries, a new button will be added under Settings > Subsidiaries - Create new subsidiary.
Create your new subsidiary and it will appear as displayed below.
Creating a new document type
Go to Settings > Documents templates and click on Add document template.
The subsidiary will be shown in the upper right corner and only serves for preview purposes.
Using your new subsidiary when creating an invoice
From now on you will have to select which subsidiary you want to invoice out of.
The document you've previously created will be added as an option you can select.