Trying to update a ticket in a separate form (with custom field)

Dear All,

I'm rather new, but hope I can get some help here.
With OSticket 1.10

I'm trying to edit a custom field, just from the view-mode,
since all my agents need to edit, is this RMA number field.
With some script-kiddie-skills I managed to do this.
Only thing is, because of the name and ID of the form input field is changing,
I can not make it permanent.
Is there somewhere a static name for my custom field,
so I can use this, in stead of the changing [03da7e1a78cc6c3e] name/id?

In "include\staff\ticket-view.inc.php" at line 209
I added some code:

<div style="display:inline-block"> 
	<form method="POST" action="tickets.php?id=<?php echo $ticket->getId(); ?>" name="update"> 
		<?php csrf_token(); ?> 
		<input type="hidden" name="a" value="edit"> 
		<input type="hidden" name="source" value="<?php echo Format::htmlchars($ticket->getSource()); ?>">  
		<input type="hidden" name="topicId" value="12">   
		<input type="hidden" name="slaId" value="1">   
		<input type="text" id="_03da7e1a78cc6c3e" size="16" maxlength="30" placeholder="COMPANY.NAME.DATE" name="03da7e1a78cc6c3e" value="" style="text-align:center;font-size:11px;line-height:16px;">
		<input type="submit" value="RMA" class="button" style="height:19px;width:25px;padding: 1px 9px 3px 5px;">  
	</form> 
</div>

Thanks in advance,