Yesterday, my supervisor at work confessed that she enjoys standing in other people's wedding family photos. She does this at Temple Square. When a big family is standing on the temple steps for a wedding photo, she stands along with them. Moves a little to the right when the photographer asks. Everyone just thinks she's on the other side of the family.
She's hoping to start a Mormon myth of the "ghost lady" in the temple picture. Years later (when the bride and groom actually know most people in their spouse's family), they'll both ponder at that wedding photo and wonder "who the heck is that?"
This "performance art" is an interesting object lesson on how Mormons tend to marry rather quickly. If a random stranger can spend a day at temple square inserting herself into family photos, I suppose that says something. Though it probably says more about that random stranger.