Thanks Ken.

I tried to keep my first post as succint and simple as possible. Maybe I've overlooked some considerations and that may be because I've assumed the task to be a simple one. ie. merge the files and move/copy/ the merged file into a new folder (which is in the same path).

1.
if I understand it correctly, currently I have 20 folders with 6 files each and the macro would run once to merge each of the 6 files in each of the 20 folders.
2. yes p2 is in the p path so the code will have to skip merging pdfs in p2 (as they have already been merged)
3a. folder1_.pdf, folder_2.pdf etc.
4. If I understand this correctly (1) is a single run

"
If you know that your subfolder names would never be duplicated, I would go with that method. So, rather than PDF_1.pdf, it would be maybe in SubFolder1\Merged.pdf and copy to p2 folder as p2\SubFolder1.pdf.
" That sounds sensible.