It's good to see you here in the Community, @St Paul.
I'll share some information on how attachments work with regard to the backup feature.
Currently, QuickBooks doesn't include attached documents when you create or share a backup file. In your case, you'll need to make a copy of the Attach folder which can be found in the same location as your QuickBooks company file. Then, you can send the backup file and a copy of the Attach folder to your accountant.
You may want to learn about QuickBooks Document Center. You can check out this article: QuickBooks Document Center: FAQs and common issues. This includes troubleshooting steps for common issues like missing attached documents, issues with scanning or attaching documents, or being unable to email transactions or send forms.
Don't hesitate to leave a comment below if you need more assistance about this, @St Paul. I'll be around to help.