If I am working on a song with my own combination of instruments and I find a RT in the 'RT picker dialog', and I then press 'Song demo' all my own instruments disappear from the mixer. Is there a way to get the first instrument combination back?
If there is a way to get it back from within the software, I haven't discovered it yet. I suspect that this is because the Song Demo button loads the BIAB chord sheet and generates from there.
That being said...
Under 'Preferences' you could select the options that tells BIAB to load multiple instances and then start up a second instance of BIAB that you could use to test run song demos. Having two instances of BIAB open would do the job for you.
I don't usually run multiple instances of BIAB. What I always do is to save the songfile before I experiment. Every time I stumble across a selection of tracks that I like, I save the file with a new name and a rating as to how much I liked it. For example,
My Latest Song 2 (5).MGU is my own system to tell me that this version of my file called "My Latest Song 2" has a rating of 5/5 - this means I really liked it! By saving the file, I simply re-open it to return to what I had before experimenting.
Sometimes, I also save an abbreviated version of the track name and number that I liked in the song title, too. For example: 'My Latest Song_accordion_2567 (5).MGU'. I've found this to be a good way of recalling the exact track I liked. And as mentioned above, the (5) rating, which means 5/5, also tells me that I really liked this version of the song.
Regards,
Noel