I’m not sure what format they are recorded in, but there are websites and programs out there to merge gps log files. I’ve used one successfully to merge tracks from a Garmin sports watch. It was a couple of years ago and I can’t recall the website I used.
So did I, I had a flight last week where my drone lost connection with the controller so it began RTH, when connection restored I cancelled RTH and continued flying for another 10 minutes or so and the whole flight was recorded as one log.
The ones that upload to AirData (.txt files) are from your device, though. Always have been.
The ones from the drone (.DAT files) are encrypted and AirData can’t open them (since some time after the M2P came out). That should be a single file, though.