For some instruments you could put the various layers pre-assigned to the MIDI channel(s) you want, Transpositions would likely have to be handled through a Staff Style.

Hmm. In what way is this faster or easier than what I did in Fin2011? I thought that six years of developing could come up with a better solution. In this case, making up expressions that change the midi channel plus staff styles for transposition is not only just as fast, but you can also see in the score at a glance where a transposition has been applied...

I can't really believe that this is the only way...

I worked like that with Finale 2011...

You are right. My suggestion is no faster than what existed in Finale 2011, but it is a way to preserve the sophisticated connection you have between your score and very specific Aria setup when moving it from 2011 to version 25.

If you started a new score and used the change instrument utility, your process might be considerably easier. You could then--after you had entered the score--arranged your playback options as you wished. The complication in your original inquiry was that you wished to preserve your 2011 arrangement while using the new features of v25. 

Thanks for your time. This is correct.

I have, however, also started from scratch since then because I found the new options intriguing and wanted to try them out. Why not use the features of a new version, right?

In a new score setup with JABB3 as a priority, the regular woodwind instruments of a Big Band load fine: Alto 1-2, Tenor 1-2, Baritone Sax. However when it gets to doublings, I am bewildered on how this works. When working in the Alto 1 staff, for example, when I make an instrument change to Clarinet, Finale loads Clarinet 1 (from JABB3) which is fine. However it's not loaded into a free Aria slot, but overwrites an existing one. So I quickly learned that I cannot use a preexisting set (with all the EQ, EFX, etc.) at all since Finale overwrites anything when doing an instrument change.

Now, when I do the same with Alto 2 (changing to Clarinet as well) Finale loaded Clarinet 1 again, although JABB3 includes three Clarinets (which Finale 'knows' about). This was the first thing I wondered. Of course in the score manager, you can change the sounds, so I decided to exchange it to Clarinet 2.

After having loaded all available doublings to all five saxes (Flutes, Clarinet, Sopranos, Bass-Clarinets) via instrument changes in mock-up bars, I started tweaking the sounds. We are talking about 5x4 = 20 sounds. This took quite a while.

However, after I deleted some bars with the instrument changes (this is something that can quite happen in the real world!) it UNLOADED all the samples from Aria along with all the settings. So ALL the settings were lost again. I tried again making an instrument change to Clarinet in Alto 2, but Finale chose Clarinet 1 again, so neither my selected sounds in the score manager, nor the setting in Aria were retained. Everything was lost.

I haven't found a way to use use the Instrument Change feature with JABB3 - or any library other than the built-in one.

Have I overlooked something?

P.S.: This problem will also happen if one uses the Garrison Finale sounds...