This is it movelist feature that we spoke about. In your request you wanted to edit a document design and then have it poll and overwrite the existing document in the directory. I have written a movelist and tested using a document design called LS.RPT

Make a text file called movelist.txt and put the following in the body of the file and save.
LS.RPT .designdocdes~1receipt

What this does is move the listed file LS.RPT into the designdocdesignreciept folder
Please be aware that this will overwrite the document design in the directory, I would suggest having a backup of that document incase you do not like the changes you can poll it back to its original state.
Another suggestion is to keep the file name to be sent under 8 characters as the process that executes the movelist is a DOS based program. I had to convert the DOCDESIGN name to a dos complainant name, DOCDES~1 so it knows where to put the file, but would not suggest it for the design name.