Combining Disheartening Display with Unchained Intimidate

[Aresirn]

With Unchained Intimidate it is possible to inflict multiple rounds of different fear effects on a target.

For example, a demoralizer with 10 ranks in Unchained Intimidate who beats their target's Demoralize DC by 15, chose to impose frighten, and rolled a 3 on their d4, would inflict 3 rounds of Frightened followed by 1 round of Shaken.

What would happen if a Disheartening Display was then used on a target who was already suffering from those fear effects?

The text for Disheartening Display says:
"When you successfully use Dazzling Display against any shaken, frightened, or panicked opponents, their fear increases by one step. An already panicked creature demoralized by this feat cowers. Once affected by this feat, a creature cannot be affected by it again (by you or anyone else) for 24 hours."

I see 3 plausible interpretations:

A. Disheartening Display upgrades the current fear effect for 1 round:
1 Panicked, 2 Frightened, 1 Shaken

B. Disheartening Display upgrades all rounds of the current fear effect:
3 Panicked, 1 Shaken

C. Disheartening Display upgrades all fear effects currently queued on the target:
3 Panicked, 1 Frightened

If there is no official guidance, how would you run it as a DM?

[Diego Rossi]

Skills unlock is an optional rule, so there is very little support for it.
Seeing how easy is to make a character with very high value in the intimidate skill while the DC of using it is relatively low I would go for the less powerful option. But it is a matter of taste, not of rules.