Hi. I just started using Dorico a couple of days ago. Really nice!
It would be helpful to have the ability to easily add an alternate rhythm above a given note. This is a common feature in Baroque music, where you might have an eighth note written in the staff, but have the alternate performance possibility of a sixteenth note written above the staff. I have tried to use the workaround of shift-X and then copying the SMuFL glyph using Bravura, but this wreaks havoc with the system spacing.
Maybe it could just be another subsection of the ornament popover, which works perfectly for adding ornaments in exactly the same space that the alternate rhythm would go (or, for that matter, ficta). It wouldn’t have to affect playback at all, since the main rhythmic option is already denoted in the staff.