I'm not sure if the rear calipers work for the service brake or not, but for sure the park brake is NFG. With the notorious rear disc pins...
This is not my car, I'm just trying to keep repairs on the cheap for a friend. It has been poorly maintained in the past and I doubt the brake fluid has ever been flushed - 200,000km+++. If I had my way, it would be getting new calipers and flex lines all round. Penny wise, pound foolish.
Tony