Adding a note to an existing chord

While inputting music, I’m having to change Dorico’s enharmonic spellings constantly and it’s costing me way too much time. Sometimes it helps to create a chord the way it needs to be spelled and then copying it, but often the chord needs to change and any attempt I make to change it removes the enharmonic changes. I was wondering if it’s possible simply to add (a) note(s) to an existing chord without deleting what was there.

Sure: select the note or chord to which you want to add a note, hit Return to show the caret, hit Q to engage chord mode, then add the note(s).

Is that true for any new chord tone or (currently) only a new top note?

You can add as many notes as you like to any existing note or chord, using Shift+Alt and Ctrl+Alt (or just Ctrl on Mac) to specify whether the new notes should go above or below the current top note.

When I hold Ctrl to add a note it seems to add a note below the lowest note. Is there a way to add a note in the middle of an existing chord without adding the note and then moving it up or down and octave?

It turns out I misspoke earlier: when you use Shift+Alt+letter, it puts the note in above the highest note in the chord; when you use Ctrl+Alt+letter (just Ctrl+letter on Mac), it puts the note below the lowest note in the chord.