Can not inline edit all columns in the front-end. The only column that in editable in the last one in the row . (see image below)

var childTable;
var childTable2;
var childTable3;
var editor; // use a global for the submit and return data rendering
var salespersonNumber;
var customerNumber;
var productNumber;

$(document).ready(function() {

   function format(rowData) {
        var childTable = '<table id="customerRows_' + rowData.salespersonNumber + '" class="display compact nowrap w-100" 
             width="100%">' +
            '<thead style="display:none"></thead >' +
            '</table>';
        return $(childTable).toArray();
    }

    function format2(rowData) {
        var childTable2 = '<table id="productRows_' + rowData.customerNumber + '" class="display compact nowrap w-100" 
         width="100%">' +
            '<thead style="display:none"></thead >' +
            '</table>';
        return $(childTable2).toArray();
    }

   function format3(rowData) { 
      var childTable3 = 
            '<table id="budgetRows_' + rowData.productNumber + '" class="display budgetDetailRow cell-border" width="85%">' +
            '<thead><tr><th>January</th><th>February</th><th>March</th><th>April</th><th>May</th><th>June</th> 
                <th>July</th><th>August</th><th>September</th><th>October</th><th>November</th><th>December</th></tr> 
            </thead >' +
            '</table>';
      return $(childTable3).toArray();
    }

    // **** Main table
    var table = $('#salespersonByBillTo').DataTable({
        dom: 't',
        ajax: {  type: 'POST',
                   url: 'getSalepersonByCustomerBillTo_SalespersonData.php',
                   data: {salespersonNumber: '5'},
        },
        pageLength:100,
        columns: [
            {
                className: 'detail-level-control_1',
                orderable: false,
                data: null,
                defaultContent: '',
                width: '8px'
            },
            { data: "salesperson",    },
            { data: 'count',  orderable: false      },
            { data: 'salespersonNumber', visible: false     }
        ],
        order: [[1, 'asc']],
    });

  // **** Event listener for opening and closing 1st level child details

   $('#salespersonByBillTo tbody').on('click', 'td.detail-level-control_1', function () {
        var tr = $(this).closest('tr');
        var row = table.row(tr);
        var rowData = row.data();

        if (row.child.isShown()) {
            // This row is already open - close it
            row.child.hide();
            tr.removeClass('shown');

            // Destroy the Child Datatable
            $('#customerRows_' + rowData.salespersonNumber).DataTable().destroy();
        }
        else {
            // Open this row
            row.child(format(rowData)).show();
            var id = rowData.salespersonNumber;
            salespersonNumber = rowData.salespersonNumber;

            childTable = $('#customerRows_' + id).DataTable({
                dom: 't',
                ajax: { 
                        type: 'POST',
                        url: 'getSalepersonByCustomerBillTo_CustomerData.php',
                        data: {salespersonNumber: salespersonNumber},
                },
                pageLength:100,

                columns: [
                    {
                        className: 'detail-level-control_2',
                        orderable: false,
                        data: null,
                        defaultContent: '',
                        width: '8px'
                    },
                    { data: 'customer'},
                    { data: 'count',
                      orderable: false
                    },
                    { data: 'customerNumber',
                        visible: false
                    }
                ],
                select: false,
            });

            tr.addClass('shown');
        }
    });

    // **** Event listener for opening and closing 2nd level child details

    $('tbody').on('click', 'td.detail-level-control_2', function () {
        var tr = $(this).closest('tr');
        var row = childTable.row(tr);
        var rowData = row.data();

        if (row.child.isShown()) {
            // This row is already open - close it
            row.child.hide();
            tr.removeClass('shown');

            // Destroy the Child Datatable
            $('#productRows_' + rowData.customerNumber).DataTable().destroy();
        }
        else {
            // Open this row
            row.child(format2(rowData)).show();
            var id = rowData.customerNumber;
            customerNumber = rowData.customerNumber;

            childTable2 = $('#productRows_' + id).DataTable({
                dom: "t",
                ajax: {
                        type: 'POST',
                        url: 'getSalepersonByCustomerBillTo_ProductData.php',
                        data: {salespersonNumber: salespersonNumber,
                               customerNumber: customerNumber
                              },
                },
                pageLength:100,
                columns: [
                    {
                        className: 'detail-level-control_3',
                        orderable: false,
                        data: null,
                        defaultContent: '',
                        width: '8px'    
                        },
                        { data: 'status' },
                        { data: 'productNumber'},
                        { data: 'productDescription' },
                        { data: 'customerShipToName' },
                        { data: 'location' }
                           ],

                select: false,
            });

            tr.addClass('shown');
        }
    });

    // *** Event listener for opening and closing 3nd level child details 

    $('tbody').on('click', 'td.detail-level-control_3', function () {
         var tr = $(this).closest('tr');
         var row = childTable2.row(tr);
         var rowData = row.data();

     if (row.child.isShown()) {
         // This row is already open - close it
         row.child.hide();
         tr.removeClass('shown');

         // Destroy the Child Datatable
         $('#budgetRows_' + rowData.productNumber).DataTable().destroy();
     }
     else {

         // Open this row
         row.child(format3(rowData)).show();

          var id = rowData.productNumber;
          productNumber = rowData.productNumber;
 
         editor = new $.fn.dataTable.Editor( {
         ajax: {
            type: 'POST',
                url: 'ssp_getSalepersonByCustomerBillTo_BudgetData.php',
                data: { salespersonNumber: salespersonNumber,
                       customerNumber: customerNumber,
                       productNumber: productNumber
                       },
              },
             
             table: '#budgetRows_' + id,
             fields: [ {
                     label: 'January Budget:',
                     name:  'BD$01'
                 }, {
                     label: 'February Budget:',
                     name:  'BD$02'
                 }, {
                     label: 'March Budget:',
                     name:  'BD$03'
                 }, {
                     label: 'April Budget:',
                     name:  'BD$04'
                 }, {
                     label: 'May Budget:',
                     name:  'BD$05'
                 }, {
                     label: 'June Budget:',
                     name:  'BD$06'
                 }, {
                     label: 'July Budget:',
                     name:  'BD$07'
                 }, {
                     label: 'August Budget:',
                     name:  'BD$08'
                 }, {
                     label: 'September Budget:',
                     name:  'BD$09'
                 }, {
                     label: 'October Budget:',
                     name:  'BD$10'
                 }, {
                     label: 'November Budget:',
                     name:  'BD$11'
                 }, {
                     label: 'December Budget:',
                     name:  'BD$12'
                 }
             ]
         } );
  
         // Activate an inline edit on click of a table cell
         $('#budgetRows_' + id).on( 'click', 'tbody td:not(:first-child)', function (e) {
             editor.inline( table.cell( this ).index(), {
                 onBlur: 'submit'
             } );
         } );
 
         childTable3 = $('#budgetRows_' + id).DataTable({
             dom: 't',
             ajax: {
                type: 'POST',
                    url: 'ssp_getSalepersonByCustomerBillTo_BudgetData.php',
                    data: { salespersonNumber: salespersonNumber,
                            customerNumber: customerNumber,
                            productNumber: productNumber
                        },
                },
             serverSide: true,
             columns: [
                              { data: 'BD$01'},
                              { data: 'BD$02'},
                              { data: 'BD$03'},
                              { data: 'BD$04'},
                              { data: 'BD$05'},
                              { data: 'BD$06'},
                              { data: 'BD$07'},
                              { data: 'BD$08'},
                              { data: 'BD$09'},
                              { data: 'BD$10'},
                              { data: 'BD$11'},
                              { data: 'BD$12'}
             ],
             select: {
                 style:    'os',
                 selector: 'td:first-child'
             },
         } );
    }

 });   
} );//END $(document).ready(function() 
} );