Here is the discussion on the 3 stave piano template, and a link to download a copy.
The discussion mentions possible success creating the desired format in another program (Finale or Muse Score) and importing into Dorico via XML.
Here is the discussion on the 3 stave piano template, and a link to download a copy.
The discussion mentions possible success creating the desired format in another program (Finale or Muse Score) and importing into Dorico via XML.