How to properly filter a dynamic get for front-end menu

[cpaschen]

I've got a dynamic get used for a front-end listing of items.

In the TWEAK tab I'm using a filter type of FunctionVar with a State Key something like this:

$this->state->get('parameters.menu')->get('catalog_new')
equal to a Table Key
a.new

The a.new field is a yes/no radio field.
The catalog_new field was also created as a yes/no radio field,
and added to the component configs so that it can be used as filters on a front-end menu.
(this is generally working)

However, I need to also allow the query to return results where the a.new field is not filtered.

I have checked the Allow Empty field; however, that just 'allows' the empty.

The problem is that the catalog_new (filtering) field doesn't have a way to 'un-set' it.

I've tried various settings on the catalog_new radio with no way to do it directly that I could figure out.
(Including: default: 0; default: -empty-; no default, - but anything other than 1 is always interpreted as 0 = no)

My only solution was to change catalog_new to a radio button with 3 options (yes,no, n/a - with 'n/a' getting a -1 value) and then to manually override (custom code) the code that was generated by JCB and just ignore when the value is -1.

I'm trying not to use custom code replace wherever possible, but I can't seem to find any way to get the TWEAK to work with this workflow.

Any ideas??