Percussion cue staff inside of grand staff

I'm writing a piece with flute and electronics (not of my own volition...) and I'd like to put a reduced piano staff of the electronics in the flute part. I'd like it to be a grand staff with a small percussion cue line in the middle of it—I've attached an image of this in another piece for reference HOWEVER it does not have the single staff line. Instead, the cue notes are floating in between treble and bass. I would like to do the same thing but with the actual staff line for percussion. I was wondering if there's an efficient way to do this. I know I could at least make three instruments (piano treble, percussion, and piano bass) but then I would have to manually adjust everything to make it look nice, whereas if I can make one instrument, it'll automatically adjust for the most part. Thanks!