How to transpose by a ninth

About the original question:

  • The interval calculator on the right makes it easy. Change the second note to D and increase the octave by one.
  • Asking to transpose Bass Clarinet by that interval makes me suspect you may want a part showing a different clef. There are different instruments that do that in Dorico. Did you actually want to change the pitches?

Edit: Now I see you’re getting advice in the other thread.