Flight Data - Merging flights

When flying a longer mission which requires landing to change batteries, it begins a new set of flight data. When updating to AirData UAV it then creates multiple flights.
I would like to see the entire flight path on AirData at once.

I downloaded the CSV’s out of AirData, then I spent a little time trying to merge several flights into one CSV file, but it didn’t seem to like that so much.
I updated millisecond time so it was continuous, and made sure I removed the header rows for each flight. (Other than the initial one.)
Is this possible? (Seems like it should be.) Has anyone done this? Any utilities to do this somewhere out there?
Tips on how to do it?
Thanks!