Some formatting stuff

I'm working on a large orchestral score, and I'm not quite sure how to do something

In lots of scores, like the one in this picture, the part names (clarinet and bassoon) are joined together, but the part numbers are separate (I & II, III). How do you do something like this in MuseScore? I was thinking when you add instruments to add a staff to the part, but when you separate the score into parts they're still linked together, so, for example, the four horn parts are all on one page, versus being split into 1-2 and 3-4