Note:

In a nutshell, the phpGrid displays the datagrid rendered by jqGrid. Select2 does the autocomplete and nested dropdown completely on the client side.
which is also the reason why the data javascript data source must be structured correctly.


Dev note:

//FORM select
$("#FrmGrid_customers tr#tr_country td select[id=country]")


//INLINE select
$("#customers tr#125 td select[id=125_country]")
$("#customers tr#125 td select[id=125_state]").select2("val", "nj");
//- OR -
$("#customers tr#125 td div#s2id_125_state > a > span.select2-chosen").text("ca");