Thumbnails
Ravenvii/commerjare
One way is to merge documents is to copy and paste from thumbnail view. Open your documents and go to view >> show thumbnails (or option-command-p). This will bring up a sidebar with page thumbnails. You can copy and paste any or all pages from one documents thumbnail view to the next.
Note that this does not copy headers/footers for some reason.
Hopefully that helps ya'll,
Erik