We may not have kept it.
Like my friend who'd returned the onesie from her mother-in-law, we've all exchanged our fair share of gifts we didn't quite need in exchange for things we did (ahem, nappies). And if, bless your heart, you stuck to the registry and gave us that trusty nappy pail, you know how much we appreciate it without needing photographic proof. So asking for documentation of a Thomas the Tank Engine crib blanket that we knew we'd never use just makes us feel unnecessarily guilty.
Our partners never seem to be tasked with this.
It irritated me to no end that I was the exclusive recipient of these photographic requests. My husband just so happened to have a camera on his smart phone, too, yet no one — not even his own relatives — came to him over me.
Gifts shouldn't come with fine print.
Bottom line: if you are truly giving a gift, you shouldn't ask for anything in return. I've found that those truly thoughtful gifts — a funny baby shirt that perfectly speaks to your sense of humour or a toy you'd really, really wanted in your nursery — are easily remembered and always, always appreciated. And from personal experience, they are the gifts I end up snapping a dozen photos of and sharing with anyone who'll look.