You can't currently include stored documents in a Visualforce email template. Instead, you would need to use Messaging.sendEmail to attach files stored in Salesforce. You can access this feature in triggers, and you can modify the workflow rule to trigger the trigger by using a field update. If you're manually sending an email, you'd have to literally write your own SendEmail page in order to dynamically add the attachments. I would say that your best option would be to re-create the PDF in an apex: attachment tag.
You can have multiple attchments using
<messaging:attachment renderAs="pdf" filename="abc"> </messaging:attachment> <messaging:attachment renderAs="pdf" filename="def"> </messaging:attachment>
based on condition make it rendered true / false
You can't currently include stored documents in a Visualforce email template. Instead, you would need to use Messaging.sendEmail to attach files stored in Salesforce. You can access this feature in triggers, and you can modify the workflow rule to trigger the trigger by using a field update. If you're manually sending an email, you'd have to literally write your own SendEmail page in order to dynamically add the attachments. I would say that your best option would be to re-create the PDF in an apex: attachment tag.