jQuery UI datepicker: startDate / endDate - Stopping selectable dates based on day of the week

Using some code now to prevent selecting an "End Date" before a "Start Sate"...

            var dateFormat = "mm/dd/yy";
            var from = $("#StartDate").datepicker({
                changeMonth: true,
                numberOfMonths: 1
            }).on("change", function () {
                to.datepicker("option", "minDate", getDate(this));
            });

            var to = $("#EndDate").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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I need to change this to also only allow a date to be selected up to the next sunday. i.e. looking at a current 2017 calendar, if I were to select today (Friday, March 10) as a "Start Date" then i would only be able to select dates through March 12, which is the next Sunday. (So only March 10, 11, and 12, would be available for "End Date"

Another example would be April 3 (Monday) is the start date.
April 4 (Tuesday)
April 5 (Wednesday)
April 6 (Thursday)
April 7 (Friday)
April 8 (Saturday)
April 9 (Sunday)
would be the only selectable options for "End Date"

How would I do this?