It sounds like you want to get the addresses changed quickly in order for the new silver cards to be posted out to the correct address so you have them in time for your trip. In reality you should be fine just using your boarding passes which will show the status of each individual for guesting purposes. Worse case you can show the silver status through each individual's app (assuming the children have devices)? If not you can log out of your account on your device and log in as each of the children to show their status in the app. I agree it makes sense to get it resolved but you should not have any problems with guesting if you don't have the physical cards to hand.