The reason I mention this is that for some odd reason, Lynn seems never to have had the idea of doing her own clumsy, irritating and cloying take on a horrible year-book photo. The Disney program "Pepper Ann" handled the subject well by having the title character ignore what she saw in the mirror every day and believe that she 'really' looked like a bog-standard ineptly-done photo by the bored clod the school hired. It seems to me that someone as obsessed with her appearance as Lynn is would naturally want to use the kids as a round-about means of complaining about the unfairness of how much the camera added to one's appearance.
It seems to me that the faulty wiring in her brain that makes her look in the mirror and see someone fat and ugly and pale and weak and unworthy of love would probably want to avoid a reminder of old defeats. It also seems to me that Lynn doesn't trust cameras much the same reason that she won't be told she's thin; since she simply cannot see herself as she really is, she probably assumes that whenever they try taking photos of her, people come back later and take a photo with some skinny person with lousy posture and tell evil, crazy lies about how the thin woman who's all hunched over is supposed to be her.