How to make instrumentgroups inside the score

I made a score for a 17 piece brassband, where I would like to split up the instrumentgroups, but how do I put all the trumpets in one group, and the trombones in another? Right now the barlines in the left side of the score is just going throug all the voices all the way down, and it makes more difficult for the conducter to read.

Hope to hear from you!
Anders