I think you can only do this with a simple 2 step process. I do this with Outlook. Compose your reply, then search for the document in DocuWare. Select Send and whatever option you need (original, pdf, etc). DocuWare will open a new message. Now, just drag the attachment from the new message to your email chain reply. Close the DocuWare generated message without sending it.
The reason for this method is that DocuWare cannot know what email message you have open, all it can do is tell the mail client to open a new message.
Senior Director Support Americas