Combining PDFs is not as simple as just appending the byte arrays to each other - in fact, it’s decidedly non-trivial. Looks like there are some command line tools you could use: https://stackoverflow.com/questions/2507766/merge-convert-multiple-pdf-files-into-one-pdf - you’d have to execute the reports and save them somewhere on the gateway, then run an external command, then load those bytes into system.perspective.download.