Splitting notes between bass and treble clefs within same hand's part

I posted this in the piano forum, but it's fallen down the page without any views. I wanted to post it in the general forum to see if there are any ideas. I am trying to type in the octave eighth notes on Chopin's Prelude 15 bar 35 with the top G# in the treble clef and the lower G# in the bass clef. As you can see in the attached score image, the simultaneously played G#'s in right hand appear split between the treble and the bass clef staves. When I try to use Command+Shift+UpArrow on just the top G#, both notes go to the treble, even when the individual top G# is selected. Is there a way to move just one of the G#'s up while the other stays in the bass staff?