They can not renew their PR cards when they are outside Canada. They need to come to Canada to send in the application to renew their PR cards. If the cards are expired, they send them back, if the cards are still valid, they can keep them. CIC will let them know when to pick up their new cards and they will have to go do it themselves.
Thank you Leon! I filled out the " Use of A representative" form or IMM 5476, does it mean that I can pick up the new PR cards for whomever that I represent?