The following JavaScript will set the checkboxes on the right frame when the corresponding checkbox with the same name is clicked on the left frame. This example presupposes that the name of the form in the right frame is "checkBoxForm" -- change this to suit your needs:
<script language="JavaScript" type="text/javascript">
<!--
function setCheckBox(cb) {
eval('parent.frames[1].document.checkBoxForm.' + cb.name).checked = cb.checked;
}
//-->
</script>
<form name="checkBoxForm">
<input type="checkbox" name="box1" onclick="setCheckBox(this)">
</form>
