Marimba Rolls

I've been using MuseScore for a couple years, and really love how I can notate almost anything. As a percussionist, I can do professional-looking exercises and transcriptions for myself and my students. However, there are a couple areas where the notation I need isn't available. The attached image shows some examples. I would like to be able to show an arpeggiated chord across all four voices on a grand staff (currently, I can only see how to show arpeggiation on one system, but not across both systems, as is necessary for marimba notation. Also, I would like to be able to show unmeasured rolls in each hand. In the example, a one-handed roll is shown by an oval across the stem, and arpeggiated rolls are shown with an elongated "S". Thank you for your consideration.