jQuery Grid Plugin - jqGrid

I have written a module that updates dropdown boxes in the multiple search process in jqgrid 3.6 interactively:

For example in the first line you have a dropdown (select element with options) to select a Country choose "France" , operator "AND" and then hit "+" :

   Then a background process updates all dropdown search boxes via Ajax and you can only choose items for "France"

in the other dropdown fields (for example you can select only regions in France , customers in France,...)  which makes specification much easier.

In jqgrid 3.6 this is easy. I just update all the select elements (class 'vdata') below the actual one (visible or not) and the rest happens automatically because jqgrid just switches between 'display:inline' 'display:none' when search fields are switched.

In jqgrid 4.0 and 4.1 the values for the options are copied from a "secret" place I could not find when switching between different search items. Now my question is:

Does anyone know where these select options are stored and how I can manipulate them with an ajax request.

Or is it possible to use the old search tool from jqgrid 3.6 in jqgrid 4.0 and how to do this?

Any help is welcome- I would like to share my code if I get this to work.

Dirk