Making pdf files with portrait and landscape pages at the same time

Right now I am the president and administrator of my building homeowners association.
Every month I send by mail a pdf with the accounting details and the list of owners with unpaid debt.
Long time ago both things were fitting in just one landscape page, but as the debt is growing, it needs its own portrait page just for it.
As accounting details are in a landscape page, the problem is how to make a single pdf ...
https://www.pdflabs.com/docs/pdftk-cli-examples/
http://www.maketecheasier.com/combine-multiple-pdf-files-with-pdftk/
No problem if 1.pdf is landscape and 2.pdf is portrait ...

pdftk file1.pdf file2.pdf file3.pdf cat output newfile.pdf

Another idea: generate a jpg from pdf. I would like to send them to some owners by Whatsapp, with does not allow pdf.
http://ubuntuforums.org/showthread.php?t=1965114

 convert -quality 100 -density 600x600 multipage.pdf single%d.jpg