You can manipulate and capture file names along with content in Drafts. You would do this via actions.
But, your description sounds like you are just concatenating text (Markdown) files.
If you are on Mac, you can do this by putting the files in a folder and using cat *.md >>../somefilename.md should concatenate them to a new file one level up.
If on iOS/iPadOS, then you could do the same sort of thing using a repeat loop in Shortcuts.
If you are wanting to use Drafts to do more than, or something different to file concatenation, can you provide details and perhaps a simple worked example?