Google Drive is Google's file sync app that lets you store all of your files online alongside your Google Docs documents, and keep them synced with all of your devices.
Assemble case PDFs in the specified page order for review.
Your report or invoice packet is ready on the same spreadsheet row as the source PDFs, with its pages in the order you chose.
Join case PDFs in order and attach the packet to the task.
Your reviewer gets a single PDF in the order you set, with the finished packet attached and linked on the project task.