Here's an easy one!  Copy + Paste this code in the Post HTML of the block on the New Family page, to automatically select the value of the Campus dropdown and the State in the Address to match the Campus (and it's state) of the Current Person working with the page.  This is most helpful when you're *not* using a shared user.

{% assign personCampus = CurrentPerson | Campus %}
<script>
$( document ).ready(function() {
    $("select[id$='Campus']").val("{{ personCampus.Id }}");
});
</script>

<script>
$( document ).ready(function() {
    $("select[id$='State']").val("{{ personCampus.Location.State }}");
});
</script>