Adding instruments to existing players

Hello all. As a relatively new user to Musescore I have to say that I'm absolutely loving it. A simple question for you. Is it possible to add an instrument to an existing player so that they are construed as one part (for example adding a piccolo to a flute player or adding a clarinet to a sax player)? I'm guessing it's possible but I just can't find out how to do it.