jQuery/javascript/bootstrap - Working with datepicker, combining two scripts, StartDate/EndDate

I have two sets of code, both which work on their own, but I'm really struggling to combine the two.
What I'm trying to do is control start date / end date entries into respective textboxes with datepicker.
When the start date is selected, the date picker disables dates before that selected date when the other text box is clicked.
Also, only days up until the next Sunday (from the selected start date) can be selected as an end date.

So this code works to disable any previous dates for the endDate textbox.

  var dateFormat = "mm/dd/yy";
  var from = $(".start").datepicker({
    changeMonth: true,
    numberOfMonths: 1

  }).on("change", function () {
    to.datepicker("option", "minDate", getDate(this));
  });

  var to = $(".end").datepicker({
    changeMonth: true,
    numberOfMonths: 1
  }).on("change", function() {
    from.datepicker("option", "maxDate", getDate(this));
  });

  function getDate(element) {
    var date;
    try {
      date = $.datepicker.parseDate(dateFormat, element.value);
    } catch (error) {
      date = null;
    }

    return date;
  }

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And this code works to only allow dates selected until the next Sunday:

<script>
var dateFormat = "mm/dd/yy";
$(document).ready(function(){
  var from = $("#StartDate").datepicker({
    changeMonth: true,
    dateFormat: dateFormat,
    numberOfMonths: 1,
    onSelect: function(dt, inst){
      var fromDt = $(this).datepicker("getDate");
      var nextSunday = new Date(fromDt.getTime());
      nextSunday.setDate(nextSunday.getDate() + 7 - fromDt.getDay());
());

      to.datepicker("option", "minDate", dt);
      to.datepicker("option", "maxDate", nextSunday);
    }
  });

  var to = $("#EndDate").datepicker({
    changeMonth: true,
    dateFormat: dateFormat,
    numberOfMonths: 1,
    onSelect: function(dt, inst){
      from.datepicker("option", "maxDate", dt);
    }
  });
});
</script>

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I need to combine the two, or have a better way to do it. I just can't seem to get them to play together.