How can I merge one session into other?

I haven’t found nothing for do it,
there are some very old topic on this one but without solution.

Thanks

There’s no way to do this “easily”. Work was done and is still buried in the source code, but it was removed from the GUI for various reasons.

The simplest “non-easy” way is to simply import all the files from the old session. How useful this is depends a lot on the nature of the session(s).

Ok thanks for reply paul.
With audio file I can export entire tracks in separate files, is not a good way but possible, but with MIDI?
The recorder MIDI files are separate in interchange folder, I can export MIDI region from timeline, but I have always only a “region” file not entire track, and I can’t combine MIDI region (…or can I?).

…I mean that seem there isn’t a way to export a MIDI composition from Ardour, the only way that I found is export separate file or using the files into the interchange folder but so I loose all the sync of the song.

that is correct: there is no way at present to export a MIDI composition as a file. You can export regions, but not combinations of regions, either on one or several tracks.