There's several reasons you might want to merge PDF documents together to create a package.  Maybe you have pages from different programs, maybe you're building a monthly report package.   There's another document here on exporting a Domus Analytics dashboard to a PDF, so check that out if you need.  A cool thing about merging PDFs is that each page doesn't need to be the same size.  Some can be landscape, some can be portrait, and you can even use different page sizes (letter, legal, tabloid, etc.).

The first step is to put all your PDF files together in one place.  For simplicity, I make sure they have good names and somewhat of an order.

There's several tools available to merge PDFs, most all of them will work fine.  You can use a desktop program, like Acrobat, or any free PDF program that supports merging.  If you use your favorite search engine and search for "merge PDF", you'll get plenty of online web-based options, too.  Adobe even has one at:  https://www.adobe.com/acrobat/online/merge-pdf.html.

Load the files, sort them to the order you want, and export them back.  Done!

You should keep the individual files around, because you might need to update one of them, change the order, and it's nice to not have to go recreate everything.