How to enter alternate note choice

Note sure how to notate this, doing a Rule of the Octave worksheet, where there’s a choice in the descending minor between dominant sixth and passacaglia natural sixth. Basically the player gets a choice which note in a chord to play

I can add it as a new voice, but then I get rests which are confusing
new voice.png
Or I can add it as an extra note to the chord (and maybe will change the note head), but then get this crazyness

Put the accidental in square brackets?

Ooh that’s clever, but how do you isolate just the accidental? I’m seeing the bracket option on the notehead but not sure about the accidental by itself.

Duh, RTFM, it’s in properties. Perfect!

Properties — Notes and Rests — Accidental