Thank you for you help. I was afraid of that. The tip with the frames is really practical but still leaves me with having to do the two mixdowns.
The qt export is a great idea. I was told, several times, that you had to do a mixdown before exporting a sequence. To be honest I have never questioned why. Could that lead to an issue? Like with the export if I do just that?
Also I was well aware of the naming problem. But there is not much I can do. Also the HHMMSS format is not really relevant. The project just wasn’t properly thought through.