Using a CDC

My sister and her son are accompanying me to South Africa next month and I have managed to snag them a couple of Gs [:D] As a special treat I have also used miles for a CDC for them as my nephew lives in Watford and his mother is flying out from Ireland the day before to him. My original plan was to arrive at LHR before them and meet them at the DTCI having checked in through the normal UC desk. Since I've done the bookings I have the e-tickets but I am just wondering will they need to have them when the CDC turns up at their door? I'd hate to think of their treat spoilt because I'm sitting in LHR with their tix and the driver is at their door insisting he needs to see them.
I know I can resolve this easily by emailing copies of their e-tix to them but the reality is that they each decided to join me at different stages and one has a straight G while the other was an L plus and upgrade. I'd hate to start the holiday with a family row because they each paid different amounts for the same seat [:w]
I know I can resolve this easily by emailing copies of their e-tix to them but the reality is that they each decided to join me at different stages and one has a straight G while the other was an L plus and upgrade. I'd hate to start the holiday with a family row because they each paid different amounts for the same seat [:w]