Thank you so much Craig - its a few hours since I started looking at this, and had I thought got done the harder parts, ie adding my lookup table, the little form to add a lodge, with a drop down looking up all the lodges, adding the associated lodges to the itinerary page, and getting it to delete the right thing. But I couldn't for the life of me get that Redirect URL changed.
But that all looks like its working now with the hidden field:
<input type="hidden" name="hiddenfield" id="hiddenfield" value="<?php echo($_GET['ItineraryID']); ?>" />
And the Redirect line changed to:
$WA_redirectURL = "index_lodge4.php?ItineraryID=".((isset($_POST["hiddenfield"]))?$_POST["hiddenfield"]:"");