Update fields dynamically

I need my code to update the Override field when the Total field value is changed to a value greater than the Sub.Total value or refresh the Discount field when the Total field is smaller than the Sub.Total field with the value, and when you add a value in the Append field or in the Discount field it updates the Total field.

In my code, the Total field is already working properly when the Add or Rebate field is updated, but I need to work in reverse as well, as I did above, that is, also update the Override and Override fields when the Total field changes.

ThisistheHTMLcode

<divid="DivOcultaBaixa" class="" style="display: none;">
            <div class="control-group span3">
                <div class="control span4" for="focusedInput">Sub. Total:</div>
                <input class="input-medium focused span6 calc" name="subtotal" id="subtotal"  readonly="readonly" type="text" value="<?php echo number_format($soma_saldo, 2, ',', '.') ?>"/>
            </div>
            <div class="control-group span3">
                <div class="control span4" for="focusedInput">Acréscimo:</div>
                <input class="input-medium focused span6 calc" name="acrescimo" id="acrescimo"  type="text" value=""/>
            </div>
            <div class="control-group span3">
                <div class="control span4" for="focusedInput">Desconto:</div>
                <input class="input-medium focused span6 calc" name="desconto" id="desconto"  type="text" value=""/>
            </div>
            <div class="control-group span3">
                <div class="control span4" for="focusedInput"><strong>TOTAL:</strong></div>
                <input type="text" id="total_val" style="background: #FFCC99; font-weight: bold;" name="total_val" class="input-medium focused span6 result" readonly="readonly" value="<?php echo number_format($soma_saldo, 2, ',', '.') ?>"/>
            </div>
            <div class="control-group span3">
                    <div class="control span4" for="focusedInput">Valor Pago:</div>
                    <input class="input-medium focused span6 calc" name="pagoparc" id="pagoparc"  type="text" value=""/>
                </div>
                <div class="control-group span3">
                    <div class="control span4" for="focusedInput"><strong>SALDO:</strong></div>
                    <input class="input-medium focused span6 calc" style="background: #FFCC99; font-weight: bold;" name="saldodev" id="saldodev"  type="text" value="<?php echo number_format($soma_saldo, 2, ',', '.') ?>"/>
                </div>
        </div>

Script js

$(document).ready(function(){
    //Quando o valor do campo mudar...
    $('.calc').change(function(){
        var subtotal = parseFloat($('#subtotal').val().replace(".", "").replace(",", ".")) || 0.00;
        var acrescimo = parseFloat($('#acrescimo').val().replace(".", "").replace(",", ".")) || 0.00;
        var desconto = parseFloat($('#desconto').val().replace(".", "").replace(",", ".")) || 0.00;
        var pagoparc = parseFloat($('#pagoparc').val().replace(".", "").replace(",", ".")) || 0.00;

        //O total 
        var total = subtotal + acrescimo - desconto;
        var saldo = total - pagoparc;

        $('#total_val').val(number_format(total,2, ',', '.'));
        $('#saldodev').val(number_format(saldo,2, ',', '.'));

    });
});

function number_format( number, decimals, dec_point, thousands_sep ) {
var n = number, c = isNaN(decimals = Math.abs(decimals)) ? 2 : decimals;
var d = dec_point == undefined ? "," : dec_point;
var t = thousands_sep == undefined ? "." : thousands_sep, s = n < 0 ? "-" : "";
var i = parseInt(n = Math.abs(+n || 0).toFixed(c)) + "", j = (j = i.length) > 3 ? j % 3 : 0;
return s + (j ? i.substr(0, j) + t : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + t) + (c ? d + Math.abs(n - i).toFixed(c).slice(2) : "");}