Numbering instruments on shared staves

[MichelRE]

I'm wondering about this since I don't have many scores that actually help me answer the question (lots of scores, just.. none that have this particular issue.)

So flute 1 and 2 share a staff in the condensed score.

The staff is labeled as Flûte 1/2 (ie: the numbers are one above the other, next to the name.)

There's a passage where only flute 1 plays. flute 2 is absent for, let's say, 3 pages of the score.

So as to not cause any potential confusion with assumptions that "Flûte 1/2" means that both flutes are playing unison during that passage, I'd number the very first note with "1°" (the French abbreviation for première = first.)

Now, this flute solo (which is not per se a "solo" simply a section where only one flute plays, amidst the other woodwinds) continues on the next page, a few bars of silence, and again only flute 1 plays for yet another page.

The question is: should each entry of 1st flute be numbered?
Or should I presume that whoever is reading the score will be intelligent enough to understand that despite the staff being labeled two flutes that only one of them is still playing here?

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A corollary question:

Flutes sharing a staff, have all harmony throughout the passage, with only the occasional unison shared note.
Should I actually WRITE "unison" for those notes? Or again make an assumption regarding the intelligence of whoever happens to be reading the score?

(Note: the two flutes share stems and beams, this isn't a situation where it would be advantageous to have independent stems and beams -up and down - for the two instruments.)

[RMK]

For your first question:

Since you use Dorico, why not turn off condensing (manually) for the flutes for those three pages? Then the Flute 2 staff will be hidden (assuming you have "hide empty staves" activated) and the score label will just show Flute 1.

For the second situation: I think showing a2 for just a single note is not acceptable. Either use a double notehead or use separate voices.

[hautbois baryton]

For the second situation, I would either use doubled noteheads, or just have one voice disappear. Since the staff is labeled appropriately, it can be understood that when they are in unison where single notes appear when mixed with harmony. You could use double stems, but I think it would be ugly and overkill.

[NeeraWM]

In this case I would only show the Flute 1 uncondensed staff and hide the Flute 2 one.
If this is not of your liking, I would add "1°" over the first system and then the same parenthesised at each new page (or left-hand page, if you're sure it will be printed).
Another solution is to have double-voicing throughout, up & down-stem, whenever there is a division or a discrepancy. You would then get the up-stem 1st flute and the bar rest for the 2nd. This was done a lot by Hofmeister in the XIX century (e.g., Popper cello concertos).

So, you have many options, choose the one you like the most and be coherent with it throughout the score.