This applies to the specific family items that are supposed to make Hidden Stairs easier to find. (Ex: Lively Scarf).
Have the item give the player a notification or sound that Hidden Stairs exist on that floor. If that would make it “too easy” (or rather, not time-consuming enough), have this notification also be a chance. For example, it will only alert the player 50% of the time.
Depending on how the game is coded, this could be as simple as a couple of “if” statements. For example, the game could give the floor a tag “srHere” when the hidden stairs are generated, which can then be checked for by whatever process makes notifications happen on-entry (or automatically check for this statement, and have it disabled unless the item is in the inventory).
Although if this part of the coding is a bunch of spaghetti, forget it, lol. But having the item be functional to a very basic level gets two birds with one stone: SRs become less binary/frustrating and Pokemon that have this category of family items will be less disappointing.