You can upload a sales invoice (SI) to AutoEntry, then publish that invoice to Sage Accounting to create an SI transaction.

By default, when you click File in your actions section of the sales invoice, 'Visible to customer' is toggled off.

This means if you email a sales invoice to a customer from Sage Accounting, the customer only sees one PDF. This is the layout created by Sage.

When you click the toggle to make it visible to a customer, when you email it from Sage Accounting the customer will see two attachments. The Sage version and the attachment from AutoEntry