multiComboFilter

We have a complex “datatable” with “multiComboFilter” and “newValues” option).
The requirement is to perform an ajax request to collect all possible values of filter only when “multiComboFilter” shows the relative dropdown list.

Here is a sample code of our solution:
https://snippet.webix.com/3shwhb17

How to statically (into datatable config object) or/and dinamically pre-set a value (it could be any value) for the filter without exec the ajax call?
The multiComboFilter seems erase values not included into dropdown list (and initially the list is empty).

Moreover, how can our solution be improved?
Extending “multiComboFilter”? Using different event?
Any suggestion is welcome.

Thanks

ping