If you want the new Kontrabass to be separate from the existing notes on the Piano treble staff, then you can go into NOTION 6 Score Setup and change the Piano staff from a "Grand Staff" (treble and bass staves) to "Standard Notation, which is a treble staff . . . 
The new bass instrument already has its own separate and independent staff . . .
Then it will look like this--but with lyrics on the Piano treble staff . . .
THOUGHTSIf you want the bass to be a
separate and
distinct instrument, then it needs to have its own staff . . .
The piano can be on a treble staff, a bass staff, or a grand staff depending on what you want it to be. . . .
In fact, you can do everything on treble staves, which is the way I do it . . .
In NOTION 6 Score Setup you can tell a treble staff to play its notes one or two octaves lower or higher, which works nicely for a range of instruments--all of which can be on treble staves . . .
Done this way, you only need to be proficient in treble clef, and then only a few notes below and above the staff . . .
Instead of having to mess with 88 or more distinct notes and a virtual maze of puzzling, special register staves, there are just (a) treble staves and (b) 12 notes and 10 or so octaves (two of which most humans cannot hear, hence are reserved primarily [a] to entertain bats, birds, cats, dogs, dolphins, porpoises, sea turtles, and whales and secondarily [b] to annoy humans who think they can hear anything over about 15-KHz, regardless of age if they ever have attended a KISS or Metallica concert) . . .
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NOTE: I learned to read and sight-sing soprano treble clef when I was in a liturgical boys choir; and it makes intuitive sense to me. A while later I taught myself how to play string bass and then switched to electric bass, with rhythm guitar coming later, followed by lead guitar. I visualize the notes as if they were on treble clef but played some number of octaves lower or higher as needed. They are the same notes, just lower or higher pitches. For practical purposes, I am good from "Middle C" (C4 in scientific pitch notation) to the note that looks like "Middle C" but is above the treble staff (A5 in scientific pitch notation). I know A5 is not "Middle C", but if there is no stem, then it looks like "Middle C"; and this is the mnemonic I use to remember it. I do everything in the key of whatever has no sharps and no flats. I used to think this was either C Major or A Minor, but then I watched a video that shows how to play all seven modes on white keys by starting the respective scales on different notes. It might be C Major, but it just as easily can be E Phrygian or D Dorian; so now I have no idea what key it is. If a note sounds like it needs to be sharp or flat, then I change it so it's sharp or flat. Knowledge is power; but being unencumbered by knowledge is better . . . ]
Scientific Pitch Notation ~ WikipediaLots of FUN!