How to change a layer-while-held layer afterwards without releasing the while-held key!

[gerhard-h]

Consider you have a convieniently reachable key mapped to (layer-while-held symbols)
but somtimes you'd prefer it to be another layer like (layer-while-held numbers).
There are ways in kanata to do this beforehand like fork chord tap-dance, but I want

1. to change the layer, after I already pressed the layer key.
2. the layer should also be released, by releasing the very same layer key.

The easy but not obvious way to do it is:

• Replace (layer-while-held symbols) with (multi (layer-while-held numbers) (layer-while-held symbols))
  (still activates symbols layer)
• now put a key with (release-layer symbols) on the symbols layer and you end up in numbers layer

done :)