How do I reverse the behavior of input key chords?

[anasouardini]

[edit: fixed some typos]

I find myself, most of the time, needing to enable a key chord in only one non-base layer instead of the default behavior which is enabling for every layer and then excluding manually.
One use case is this kinda complex layering:

;; complex layering, for quick switching between often sequenced layers
;; instead of leaving a layer to go to the next, nest them
;; - numbersL (ui)
;;   - symbolsL (o)
;;     - symbols2L (p)
;;   - symbolsL (op)
;; - symbolsL (uio)
;;   - symbols2L (p)
;; - symbols2L (uiop)

So, I imagine I'd do ui to bring the numbers layer up and then simply add o with my ring finger to get fist layer symbols then p for the 2nd. Sounds like an unnecessary complexity but it feels slightly better in practice.
In general, I need to have an input key chord specific only to some specific layer and I find it unwise to remember to add new layers to the exception list of the chords.

[jtroo]

It's not possible built-in today.

As a workaround you might consider using list variables for your exclusion so it's at least easier to maintain.

(defvar
  only-symbolsL (numbersL symbols2L ...))
  only-numbersL (symbolsL symbols2L))
  ...
)

[anasouardini]

Oh! thanks, variables would definitely make it easier.