The case, that the different sections are from different persons, is not handled
In (link removed) I tried for the first time to use gpxedit to save all the gpx tracks into one single .gpx and to create sections with gpxmotion (updated nicely via nextcloud app to newest version). These sections originate from gpx tracks from different persons, but they are connected by straight lines, which should not be. A possible algorithm would be to not connect adjacent sections if there is a common time interval shared by the two sections. In this case the colour of the track should change I think. Of course what I really want in this case is finally to have all sections with shared time interval drawn simultaneously in different colours (like gpxpod animated). I make this issue confidential, because I see that (especially with loop=1) it causes quite some load on the system.