Showing one (or more) measures of a system's staff manually

An alternative title for this post might be: Hide/Show/Hide a staff in a system.

I have two vocal parts. The parts are almost entirely unison with rare occasions of harmony. I want to show the momentary harmony part (part 2) on a separate staff for just the moment the harmony occurs.

So , this would look like one staff in a system (part 1/unison), and occasionally, something like a “hanging measure” would appear below the staff in the middle of a system (part 2’s harmony). This would look like a full-size ossia measure shown below the staff (but it’s not an ossia of course).

(These are very young singers. I do not want to use divisi in a single staff.)

Is this possible in any Dorico version?

With Solo Players, you can add a Staff above or a Staff below. These, unlike Divisi, can be in the middle of a system.