Datatables column select filtering - how to disable filtered out values in select box?

Using the datatables.net example Individual column searching (select inputs) with the example javascript to append SELECT menus into the footer:

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$(document).ready(function () {
    $('#example').DataTable({
        initComplete: function () {
            this.api()
                .columns()
                .every(function () {
                    var column = this;
                    var select = $('<select><option value=""></option></select>')
                        .appendTo($(column.footer()).empty())
                        .on('change', function () {
                            var val = $.fn.dataTable.util.escapeRegex($(this).val());
 
                            column.search(val ? '^' + val + '$' : '', true, false).draw();
                        });
 
                    column
                        .data()
                        .unique()
                        .sort()
                        .each(function (d, j) {
                            select.append('<option value="' + d + '">' + d + '</option>');
                        });
                });
        },
    });
});

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Question:
how to modify the JavaScript to dynamically change the filter SELECT menus to only show values from the filtered selection. For example, after selecting Tokyo it should now limit "Position" to "Accountant, Integration Specialist, Support Engineer, Regional Marketing":

(Disabling the "invalid" select values would be an option as well using <option value="..." disabled>...</option>)

I was able to solve this for my use case. See @andrewJames comment's above about possible UI issue and how to get around it.
In my use case it works fine to disable SELECT OPTIONS that would result in 0 records shown. I'm also using a "reset filter" button

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<!-- language: lang-js -->

$(document).ready(function () {
    $('#example').DataTable({
        initComplete: function () {
            this.api()
                .columns()
                .every(function () {
                    var column = this;
                    // small change to add ids to the SELECT boxes
                    var column_idx = column.index()
                    var select = $('<select id="column_' + column_idx + '"><option value=""></option></select>')
                        .appendTo($(column.footer()).empty())
                        .on('change', function () {
                            var val = $.fn.dataTable.util.escapeRegex($(this).val());
 
                            column.search(val ? '^' + val + '$' : '', true, false).draw();
                        });
 
                    column
                        .data()
                        .unique()
                        .sort()
                        .each(function (d, j) {
                            select.append('<option value="' + d + '">' + d + '</option>');
                        });
                });
        },
    });
});

// gets called on first load and every time filter or search changes
footerCallback: function ( row, data, start, end, display ) {

    // loop over all columns - hard coded in my example    
    for (var col = 1; col < 15; col++) {                    
        column_id = 'column_' + col
        // retrieve the unique column value after a filter has been applied
        column_values = api.column( col, {search:'applied'} ).data().unique()
        // get the select box by id
        var sel = document.getElementById(column_id)
        // on first page load select box isn't rendered yet
        if (sel != null){
            op = sel.getElementsByTagName('option');
            // disable all select options that are not included in the "available" values
            // we start at 0 because we don't want to disable the blank default                        
            for (var i = 1; i < op.length; i++) {
                if (Array.from(column_values).includes(op[i].value)){
                    op[i].disabled = false
                } else {
                    op[i].disabled = true
                }
            }
        }    
    }    
}

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