Multiple PDF files to merge: macOS 10.14.3 (High Sierra)
Set at the beginning of the PDF-files via "preview (default)" will be opened. Click with the right mouse click (secondary click) on the PDF file. Select "information". There under the point "Open with" preview. Then go to "change All".
- Select the PDF files you want to merge and open them with a double click.
- You go in the menu bar, point to "appearance" and click on the Option "Thumbnails". On the left side you will see the documents in preview.
- Select the Thumbnails of the pages that you want to drag the other PDF file. Press and hold the selection and drag it to the Thumbnail of the other PDF file.
- The PDF file will automatically be saved. The file Name of the unmarked PDF remains.

Mac: PDF merge
So you are on the go with your iPad, PDF documents can edit, we have them in this practice tip a selection of PDF Apps compiled.