the events table should not contain any information that is duplicated from the Organisers like FName, Surname, Location.
only the OrgID should be stored in the events table to create a relationship between the event and the orginizer.
your link should pass the OrgID as a querysting variable
<a href="eventInsert.php?OrgID=<?php echo $row_RecordsetName['OrgID']; ?>">Insert new event</a>
where RecordsetName is the name of the recordset on the detail page.
then create a hidden form element to capture the Querystring variable in the eventInsert.php page:
<input type="hidden" name="OrgID" value="<?php echo((isset($_GET["OrgID"]))?$_GET["OrgID""]:"") ?>" />