Heated screen into defender

Hi, I've put a heated screen in the defender now onto wiring it up, just wondered if anyone had put a disco relay into it and if they work ok?
Also can anyone confirm if the relay for the front screen and rear window are the same relay as I can only see one on auto data
Thanks very much

If anyone else is having same problem I've just found these
http://www.mobilecentre.co.uk/index.php?main_page=product_info&cPath=60_127_210&products_id=577

Seem expensive but saves some trouble