Merging is simple until page 1 of the wrong packet lands first. On FiloPDF Merge PDF, add every file, then use the ↑↓ controls so the list matches the final reading order.
Turn on “Reset page rotation” if some scans are sideways - otherwise merge keeps each file’s rotation metadata.
Need only a few pages from a fat PDF? Split those pages first, then merge the pieces you actually want.
Related tool: Open merge pdf
