I’m not any good in writing for brass band. I did write all the pieces I published in Belgium for brass band and fanfare band as well as Concert band, but I didn’t have enough experience to do it right I think. It’s a craft on its own.
There are usually a fixed number of players, and many similar instruments in a brass band. There are two rows of cornets, but they are split up in different parts.
One has to think of the range and timber of different instruments and how they can be put together to produce different sound effects.
In a wind ensemble the woodwinds usually have all the runs but in a brass band the different brass instruments have to do it theme selves. Therefore you will see a quite different use of instruments. At least in the higher grade levels.
Here’s a link that explains all this further.
https://www.bandsman.co.uk/writing.htmHere’s a link to scores. It’s a German site but just type in brass band or title and you can download a PDF and listen to the piece. There may be other sites as well.
https://www.blasmusik-shop.deYou can also look at Hal Leonard Brass Band on YouTube.
https://www.youtube.com/channel/UCXaF8hZUztMmqeIvHhI3fQwI hope this can be of help.

Morten