In my score, trumpets and horns and tubas are bracketed by default.
The trombones are defined as alto, tenor, and bass, and are not bracketed. I would like them to be.
Can’t seem to find anything about this – not in the manual, not on the forum, not in the application itself.
(But the answer is probably as usual right before my eyes somewhere … I just need a little help to spot it!)
Is this a score you’ve entered directly into Dorico or imported from MusicXML?
Directly into Dorico. I could (and should?) have made it easier for myself by simply adding three trombones instead of choosing alto, tenor and bass. Then the bracket would have appeared just the way it did for trumpets and horns. After that, I could simply have changed the names in the players list and changed clefs in the score. On the other hand, it would be good to also have the option to create such a custom bracket.
It’s worth switching to Engrave mode, choosing the “Engrave”->“Engraving Options” menu item (or pressing Command-Shift-E or Ctrl-Shift-E) and looking at the options under “Brackets and Braces” to see if there anything there that might have the desired effect.
Yes, I had a look and another look, couldn’t find. I’ll use my workaround anyway, it’ll do fine.
When setting up a big band score I want to keep the saxes in one bracket, trumpets in one and trombones in one, whithout any secondary brackets. I Also want that barlines to be separated between trumpets and trombones. This is impossible to achieve with the current settings in Engraving options.
As a conductor this is how I want the score to look, with a clear separation between trumpets and trombones.
The options available now are:
• (Orchestral): Brackets on saxes and the whole brass with secondary brackets on altos, tenors, trpts & trbs. The option “no secondary brackets” doesn’t work at all.
• (Wind band): Brackets on altos, tenors, bari alone, trpts, trb 1-3, bass trb alone.
Neither of these produce a good result in my opinion. I’d strongly recommend working out a way to customize the way brackets and/or secondary brackets appear. Or maybe just add a big band setting in Engraving options.
I think you’re probably right that we need a dedicated big band bracketing style, Mats. I’ll add this to our list.
Thanks for the Big Band setup in the update! 
Have you tried to create different groups in setup mode? You can add any combination of instruments - I think - in one group and than they will be bracketed (and barlined) together, but separated to the other groups. I was successful to get this for my junior concert band with flute-oboe-bassoon / clarinet-bass clarinet / Alto-Tenor-Baritone Sax / Glockenspiel / Perc. I + II. As you see I did not add instruments of different families together, but with a Big Band setup this should be ok. I do not know about cross family marriages 
There is a different topic “Braces!” (without quotes) by Vaughan Schlepp where there is a lengthy discussion about this, and “changing instrument groups” by dfroom. Searching the forum is challenging, see → “Forum search”.
