I didn't realize it was a checkbox. This code:
$UpdateQuery->bindColumn("shawn", "c", "".($_POST["Shawn_".$MultipleUpdateCount]) ."", "WA_IGNORE");
Should be:
$UpdateQuery->bindColumn("shawn", "c", "".(isset($_POST["Shawn_".$MultipleUpdateCount])?"1":"0") ."", "WA_IGNORE");
$UpdateQuery->bindColumn("becky", "c", "".(isset($_POST["Becky_".$MultipleUpdateCount])?"1":"0") ."", "WA_IGNORE");