I think the only issue you are having is with pre-selecting the values in the select list. Everything else is the same as the insert page.
On the select update page line 229, try replacing this code:
php:
<?php if (!(strcmp($WADAMenuavsettfor_id->getColumnVal("id"), (isset($_GET["invalid"])?ValidatedField("laromedelupdate","avsettfor_id"):"".$WADAlaromedel_update->getColumnVal("avsettfor_id")."")))) {echo "selected=\"selected\"";} ?>
with this:
php:
<?php if (in_array($WADAMenuavsettfor_id->getColumnVal("id"),isset($_GET["invalid"])?ValidatedField("laromedelupdate","avsettfor_id"):explode(", ",$WADAlaromedel_update->getColumnVal("avsettfor_id")))) {echo "selected=\"selected\"";} ?>
Did this help? Tips are appreciated...
