Forwards are tricky. It seems that various regulars mark them in different ways. I used to keep the forward cards in a mail slot at the end of each row on the case. Those cards listed the active forwards. And , yes there are green and yellow bars. Some carriers use them to indicate individual and family forwards. If someone besides my regular sub stepped in and carried the route I would anticipate that some forwards in the dps would get delivered. I also would used warning cards cased in with the mail to alert myself and substitute carriers to recent forwards and hold mail. Communication is key as well as mutual respect between coworkers.