On Christmas Eve we let her put them back under the tree.
As you can see, they didn't stay under the tree for long. Both girls got tons of enjoyment from all their gifts while they were still (mostly) wrapped.
As bedtime approached we let them open their matching Princess PJs and Daddy read The Christmas Story (I can't wait until they're old enough to start acting it out!).
Elizabeth was determined NOT to go to bed. She was not leaving her treasure hoarde! We let her sleep like this for a couple of hours before Daddy carried her to bed, protesting loudly even half-asleep!
But of course she had to go to bed so Santa could work his magic. (Pretty gender-balanced for a house of 2 little girls, don't you think?)