I tried the new arranging tools in Dorico. If you have a homophonic part in one instrument, it’s no problem to split it up in 2 other instruments (as seen in part 1). If you have homophonic and polyphonic parts, it works only on the polyphonic parts. Bug or feature?
I have a big orchestral work here (33 parts), the original arranger (with Finale) always wrote 2 woodwinds in 1 system, I have to split them. So of course it would be easier if Dorico doesn’t handle it that way.
Work your way through the music in sections, taking the music separately: select the next chunk of music that uses a single voice consistently, and Explode that, then select the next chunk of music that uses two voices consistently, and Explode that.
If you are in a hurry you could ask the original arranger to run the (free included) TG plugin “Process extracted part…” (which can be used anywhere, not only on parts.) before handing you the files
