Great idea. I too would like this. It does not seem possible, though. - But it should be possible to add text to the photo of the contace in Apple Photos. You can then go to iPhone settings and make your iPhone use the option to show the photo in full screen mode like it was in earlier IOS versions. - You will have to change the text when John and Jenny get's a litte sister, though. So let us hope that your solution comes someday.