email template with attachments

So I need to save an email template with attachments. Using High Sierra OS

I previously had a saved email in a specific mailbox, that had signature block and two attachments on it. All I had to do was highlight the email, click send again and put in whatever I needed.

I now need to change some of that email, and I tried making a message, in drafts and then moving it to this mailbox, now when I use "send again" it does not include my signature block or attachments when it opens the email.

I tried using the Save as Stationary function, but it does not want to save with attachments, and anyways, I don't want it in the "stationary" folder.

Thanks in advance for any help